This is an extensive overview of the role of HLA in determining various health and disease predispositions.

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ROLE OF HLA
IN HEALTH & DISEASE
Presented by Dr. Anuja Joshi

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1. Components of the Immune response
2. Introduction to HLA
3. Historical background of discovery of HLA
4. HLA genome
5. HLA nomenclature
6. HLA in health: MHC proteins & Role
7. HLA in Organ transplant
8. HLA typing
9. Associations with Autoimmune disorders & infections
10. Future: Newer associations and learning
PRESENTATION FLOW

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Physical barriers
Innate response
Adaptive response
COMPONENTS OF THE IMMUNE RESPONSE

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Human Leucocytic Antigen – HLA complex
• Highly polymorphic gene complex located on chromosome 6p in humans encoding the Major
Histocompatibility Complex (MHC) proteins in humans
• Allo-antigens
• MHC Class 1, 2 & 3
MHC class 1 : HLA-A, B & C; E,F,G
MHC class 2: HLA-DP, DQ & DR; DM, DO
MHC class 3 – Complement system – C2,C4, TNF & HSP
INTRODUCTION TO HLA

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1950s 1960s . 1970s 1980s 1990s
Peter Medawar
Father of Transplantation
Graft rejection
Non-self antigens
Macfarlane Burnet
Clonal Selection theory
Tolerance of self
Discovery of Thymus,
T & B lymphocytes
Jacques Miller
Jean Dausset
Identification of HLA & gene
complex
MHC Restriction
Peter Doherty & Rolf Zinkernagel
1967 – WHO sets up first
committee for naming &
classifying HLA
HISTORY – DISCOVERY OF HLA

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Letter Significance
N Null allele (produces a non-functional protein)
L Lower than normal cell surface expression
S Soluble protein not found on cell surface
Q Questionable (allele may affect normal expression)
C Protein that is present in cytoplasm but not cell surface
A Aberrant expression (uncertain if protein is expressed)
NOMENCLATURE OF HLA

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HLA GENOME & POLYMORPHISMS

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HLA IN HEALTH

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MHC: Major Histocompatibility proteins
Major MHC class I
There are 3 major and 3 minor MHC class I genes in HLA.
HLA-A
HLA-B
HLA-C
Minor genes: HLA-E, HLA-F and HLA-G.
Major MHC class II
There are 3 major and 2 minor MHC class II proteins encoded by the HLA.
HLA-DP, HLA-DQ, HLA-DR
Minor: HLA- DM and HLA- DO
Major MHC class III
Complement C2, C4, TNF, HSP
MHC CLASSES

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MHC CLASS 1 & 2

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MHC 1 MHC 2
Structure MHC class I molecules consist of one
membrane-spanning α chain (heavy chain)
produced by MHC genes, and one β chain
(light chain or β2-microglobulin) produced
by the β2-microglobulin gene
MHC class II molecules consist of two
membrane-spanning chains, α and β, of
similar size and both produced by MHC genes.
Type of APC Nucleated cells, and platelets but not RBCs
(*Bg)
Professional APCs: macrophages, dendritic
cells
Nature of antigen Endogenous peptides & intracellular viruses Extracellular bacteria, parasites
Presented to Cytotoxic T cells - CD8+ cells Helper T cells - CD4+ cells
Enzymes Responsible
for peptide
generation
Cytosolic proteasome Endosomal and lysosomal proteases
Site of peptide loading
of MHC
Endoplasmic reticulum Specialized vesicular compartment
End Result
Presentation of foreign-intracellular antigens
or altered self-antigens; targets cell for
Presentation of foreign extracellular antigens;
induces antibody production, and attracts

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ANTIGEN PRESENTATION PATHWAYS
Cross-presentation* refers to the display on
MHC class I of peptides from extracellularly
acquired antigens

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CO-STIMULATION
Signal 1:
T Cell receptor-MHC
Signal 2:
CD28 – CD80 & CD86

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IMMUNE TOLERANCE

15. Unique case of tolerance of paternal allo-antigens in
the Foetus – the Placenta creates an “immunologically
privileged site”
Evolutionary step * different from Transplantation
Proposed theories:
• Induction of paternal antigens prior to actual
conception
• Role of T-reg cells
• No MHC 1&2 expression in trophoblast tissues
• Increased Cytokine production which inhibits cell-
mediated immunity
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IMMUNE TOLERANCE IN PREGNANCY
Failure of tolerance:
• Spontaneous miscarriage,
• Rh incompatibility,
• Pre-eclampsia

16. • Gut, Respiratory lining & Skin
• Acquired tolerance starts at birth – role of breast milk
• Delicate balance between extent of colonization
• Sentinel surveillance by T cells – mucosal firewall
• Downregulation of MHC expression
• Tolerance improves development of Peyer’s patches, CD8 cells
• Recent changes: antibiotics, changes in diet-
Higher incidence of Autoimmune, Allergic disorders
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IMMUNE TOLERANCE OF THE NORMAL MICROBIOME

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HLA & ORGAN TRANSPLANT
Perils of a normally functioning HLA!

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• HLA antibodies* - alloimmunization: induced by pregnancy, multiple transfusions or prior
transplantation
• Independent of ABO compatibility
• Role of Bg antigens : (Bennet & Goodspeed Bga is analogous with HLA-B7, Bgb analogous with HLA-B17 ; Bgc with HLA-A28, cross-reactivity )
• Platelet refractoriness*
• TA-GVHD – Transfusion associated Graft-versus-host-disease
• Role of irradiation of blood products
• TRALI – Transfusion related acute lung injury
• Scope for Matching in long-term / repeated transfusion requiring cases? – Feasibility
HLA AND TRANSFUSIONS

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• HLA disparity between hematopoietic stem cell (HSC) donor and recipient – graft failure
• Antigen match* - High-resolution (HR) matching at 4 loci (8 alleles), that is, HLA-A, -B, -C, and -DRB1 - (8/8)
or expanded to 10/10 (includes HLA-DQB1) alleles.
• Perfect HLA match between HSCT donor and recipient - crucial, but often not available.
• The HSCT from the alternative mismatched donor with one allele/antigen mismatch (9/10) can be as
beneficial as a HSCT from a fully matched donor, especially in younger patients.
• Permissiveness depends not only on the potential adverse effect of the HLA mismatches, but also on the
urgency of the transplantation, the desirable GVL effect and the potential efficacy of the alternative therapy
available for the patient.
HLA AND BONE MARROW TRANSPLANT

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Direct allorecognition : Acute rejection : Donor DC present donor peptide mounted on donor MHC molecules to
recipient’s T cells (passenger leukocytes)
Indirect allorecognition: Chronic rejection: Recipient’s DC acquire allogeneic donor antigens and present donor
these MHC-derived peptides to recipient’s T cells.
HLA antibodies: Hyperacute rejection
CDC cross-match:
• Because T cells express class I antigens and B cells express both class I and II antigens, the interpretation of T cell
together with B cell cross-match will help to establish whether class I and/or II anti-HLA antibodies are present.
• A positive B cell CDC crossmatch invariably accompanies a positive T cell CDC cross-match but this may reflect
either anti-HLA antibodies to class I antigens and/or multiple antibodies to class I and/or II antigens. However, a
positive B cell CDC cross-match may occur in the absence of a positive T cell CDC cross-match and suggest the
presence of class II antigens or low levels class I antigens.
• The presence of a positive T cell CDC cross-match is an absolute contraindication for transplantation whereas a
positive B cell cross-match is a relative contraindication because of the uncertainty regarding the clinical
significance and the possibility of false-positive result
HLA AND KIDNEY TRANSPLANT

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HLA AND LIVER TRANSPLANT
HLA matching - Rarely undertaken for liver
transplantation so far
Measures of outcome of liver Tx:
Age, extent of transplantation, condition of patient
around Tx and available waiting time
Initial years – logistic challenges-
• The scarcity of donor organs
• Poor condition of the patient at referral for
transplantation
• Challenges in maintaining graft viability - cold
ischemic time limited to less than 12 hours
• Early results failed to show any benefit from HLA
matching and cases of acceptable outcomes even
in non-matched events
Liver an Immunologically privileged site?
Greater expression of MHC -2 as compared to MHC-1
in the liver
Complex tolerogenic mechanisms in the liver –
largely due to its structural architecture – large
surface area, extensive sinusoidal network
Role of IL-10 and PDL-1 – downregulate T cell activity
and increased levels of these found in the liver
However, long-term rejection secondary to MHC-2
now being recognized – eventually HLA typing will be
preferred wherever feasibility allows

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HLA AND HEART TRANSPLANT
HLA matching – presently not done, infeasible – future possibilities being considered
All logistic challenges similar to liver transplant – much more enhanced for heart transplant – sicker patient,
extremely narrow cold ischemic time and critical transport
Advent of external support devices now changing the paradigm of heart transplant in triaging patients for
whom transplant should be actually done : LVAD – Left Ventricular Assist Device, Total artificial heart –
Syncardia

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HLA IN DISEASE

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MHA class 1 deficiency :
• Failure of TAP-1 molecule in transport of peptide
• CD8+ deficiency – recurrent viral infections
• CD4+ & antibody normal
MHA class 2 deficiency – Bare Lymphocyte syndrome
• Transcription defect
• No presentation by APCs hence no CD4+ activation & Antibody production
• SCID-like presentation
• Fatal in early life
HLA DEFICIENCY

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HLA ASSOCIATIONS – AUTO-IMMUNE DISEASES

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Approximately 90% of people with AS express the HLA-B27 genotype, But only 1–2% of individuals with the HLA-B27 genotype develop the disease. However, in
symptomatic patients - negative predictive value 98%
Possible theories:
• Abnormal forms of the HLA-B27 heavy chain and their recognition by leukocyte immunoglobulin-like receptors on immune effector cells, and
• HLA-B27 heavy chain misfolding and intrinsic biological effects on affected cells
• Klebsiella pneumonia (KP) infection and HLA-B 27 have been shown to be strongly associated with ankylosing spondylitis (AS) – molecular mimicry*
HLA & ANKYLOSING SPONDYLITIS
https://www.ncbi.nlm.nih.gov/pubmed/1298592
[Role of enteric Klebsiella pneumonia infection and HLA-B27 in ankylosing
spondylitis]Huang F1, Cai XH, Shi GY.
Armstrong RD, Panayi GS, Welsh KI. Histocompatibility antigens in psoriasis, psoriatic
arthropathy, and ankylosing spondylitis. Annals of the Rheumatic Diseases.
1983;42(2):142-146.

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• Children with DR-DQ haplotypes DRB1*03:01-
DQA1*05:01-DQB1*02:01 (abbreviated “DR3”)
and DRB1*04:01/02/04/05/08-DQA1*03:01-
DQB1*03:02/04 (or DQB1*02; abbreviated “DR4”)
have a risk of approximately 1 in 20 for a diagnosis of
T1D by the age of 15 years.
• If the child has the high-risk genotype and has a
sibling who has T1D, the risk is even higher (~ 55%) .
• Some haplotypes confer strong protection from
disease, such as DRB1*15:01-DQA1*01:02-
DQB1*06:02 (abbreviated “DR2”; OR = 0.03; 95% CI,
0.01–0.07)
• ROLE OF SCREENING*
HLA & TYPE-1 DIABETES MELLITUS
Noble JA, Valdes AM. Genetics of the HLA Region in the Prediction of Type 1
Diabetes. Current diabetes reports. 2011;11(6):533-542. doi:10.1007/s11892-011-0223-x.

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Initially RA was reported to be associated with DRB4.
Later – shared epitopes hypothesis discovered:
RA-associated DRB1 alleles also encode a common sequence of amino
acids corresponding to residues 67-74 (shared epitopes – SE) .
Several SE-positive (SE+) DRB1 alleles associated with RA include
DRB1*0401, *0404, *0405 and *0408 as well as the DRB1*0101, *1402, and
HLA & RHEUMATOID ARTHRITIS
Fugger L, Svejgaard A. Association of MHC and rheumatoid arthritis: HLA-DR4 and rheumatoid arthritis -
studies in mice and men. Arthritis Research. 2000;2(3):208-211. doi:10.1186/ar89.

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Patients with psoriasis had a significantly raised frequency of HLA-Cw6.
Those with arthritis in addition to their psoriasis also had raised frequencies of
HLA-B27 and DR7.
In patients with psoriasis only, the presence of Cw6 was associated with a
significantly earlier age of onset.
Woodrow JC, Ilchysyn A. HLA antigens in psoriasis and psoriatic arthritis. Journal of Medical Genetics.
1985;22(6):492-495.
HLA & PSORIASIS

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• More than 95% of celiac patients share the major
histocompatibility complex II class human leukocyte antigen
(HLA) DQ2 or DQ8 haplotype;
• Patients negative for both types are unlikely to suffer from
celiac disease - Very high Negative predictive value- almost
100% – independent of dietary gluten content
• The positive predictive value of HLA DQ2/DQ8 is however
limited as they can be present in approximately 40% of the
general population, most of whom will never develop CD
Am J Gastroenterol. 2002 Mar;97(3):695-9.
HLA-DQ typing in the diagnosis of celiac disease.
Kaukinen K1, Partanen J, Mäki M, Collin P.
Pallav K, Kabbani T, Tariq S, Vanga R, Kelly CP, Leffler DA. Clinical utility of celiac disease associated HLA
testing. Digestive diseases and sciences. 2014;59(9):2199-2206. doi:10.1007/s10620-014-3143-1.
HLA & CELIAC DISEASE

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• HLA-DR3 was related to the presence of anti-
Ro/SSA or anti-La/SSB, or both. HLA-DR3, DR9,
DR15 were potent risk factors for SLE.
• HLA-DR4, DR11 and DR14 were identified as
protective factors for SLE.
Smolen JS, Klippel JH, Penner E, et al. HLA-DR antigens in systemic lupus erythematosus: association
with specificity of autoantibody responses to nuclear antigens. Annals of the Rheumatic Diseases.
1987;46(6):457-462.
Value of HLA-DR genotype in systemic lupus erythematosus and lupus nephritis: a meta-analysis.
Niu Z1, Zhang P, Tong Y.
HLA & SYSTEMIC LUPUS ERYTHEMATOSUS

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HLA-DRB1*15:01 has the strongest effect
with an average odds ratio of 3.08 towards
susceptibility.
Several others under study
Hollenbach JA, Oksenberg JR. The Immunogenetics of Multiple Sclerosis: A
Comprehensive Review. Journal of autoimmunity. 2015;64:13-25.
doi:10.1016/j.jaut.2015.06.010.
HLA & MULTIPLE SCLEROSIS

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Early studies showed association of HLA-DR3 with Graves’
disease (GD) - amino acid substitution at position 74 of the DR
beta 1 chain of HLA-DR3 (DRb1-Arg74),with increased
susceptibility to Graves’ disease
Increasing evidence for a genetic interaction between
thyroglobulin variants and DRb1-Arg74 in conferring risk for
GD.
POST-PARTUM THYROID DYSFUNCTION - PPTD
Compared with a local control population (n = 600), and using
multiplex analysis, there was a significant increase in the
combinations HLA B8, DR3 and HLA Al, B8, DR3 from 22.5%
to 40.0% (P<0.02) and from 18.6% to 35.6% (P<0.01)
respectively in the women who developed PPTD.
Jacobson EM, Huber A, Tomer Y. THE HLA GENE COMPLEX IN THYROID AUTOIMMUNITY: FROM
EPIDEMIOLOGY TO ETIOLOGY. Journal of autoimmunity. 2008;30(1-2):58-62.
doi:10.1016/j.jaut.2007.11.010.
HLA & GRAVES DISEASE

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DR2, DR9, and DRB1*0103 were positively
associated with ulcerative colitis, and a negative
association was found for DR4 and ulcerative
colitis.
For Crohn's disease a positive association was
found with DR7, DRB3*0301, and DQ4 and a
negative association with DR2 and DR3.
Stokkers P, Reitsma P, Tytgat G, van Deventer SJH. HLA-DR and -DQ phenotypes in inflammatory
bowel disease: a meta-analysis. Gut. 1999;45(3):395-401.
HLA & INFLAMMATORY BOWEL DISEASE

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Tumour escape*
Downregulation of MHC -1 expression linked with progression of
cancers, whereas preserved MHC associated with better
outcomes
Upregulation of IL-10 and PDL-1 leading to immunosuppression
MECHANISMS:
T-cell antigen recognition failure - antigen loss/mutation
Immunosuppressive proteins
Dhanik A, R. Kirshner J, MacDonald D, et al. In-silico discovery of cancer-specific peptide-HLA
complexes for targeted therapy. BMC Bioinformatics. 2016;17:286. doi:10.1186/s12859-016-1150-2.
HLA & CANCER

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Dendritic cell therapy:
Involves the extraction of mononuclear
(CD14+) cells from the patient's own
blood, transformation of these cells into
cancer-fighting cells and giving back to the
patient.
Sipuleucel-T (Provenge):
Approved for metastatic castration-
resistant prostate cancer - fusion
protein PA2024
Newer research:
Role of targeting specific MHC-1 peptides
derived from tumour cells in targeted
immunotherapy for cancer
HLA & CANCER IMMUNO-THERAPY

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HLA-DRB1 in allergic asthma,
HLA-DQB1 in occupational asthma and
HLA-DPB1 in aspirin-sensitive asthma.
West Bengal study
Confirmed significantly higher frequency
of HLA-DRB1*03 in asthmatics -
implicated in the susceptibility to
asthma in the pediatric population.
Role of Biological – Immunotherapy*
HLA and asthma phenotypes/endotypes: a review. Kontakioti E1, Domvri K1, Papakosta D2, Daniilidis M3. Tissue
Antigens. 2014 Sep;84(3):316-20. doi: 10.1111/tan.12403. Epub 2014 Jun 25
A study of the association of childhood asthma with HLA alleles in the population of Siliguri, West Bengal, India. Lama M1, Chatterjee
M, Chaudhuri TK.
HLA & ASTHMA

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HLA & AUTOIMMUNE HEPATITIS
• AIH-1 is associated
with the presence of
DRB1*0301,
DRB3*0101 and
DRB1*0401 alleles,
• AIH-2 is associated
with DRB1*0301 or
DRB1*07.

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HLA ASSOCIATIONS – INFECTIOUS DISEASES

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• Resistance conferred
factors: B*53:01, DQB1*05:01, DRB1*01:01
, and DRB1*13:02;
• Increased Susceptibility
factors: A*30:01, A*33:01, DPB1*17:01,
and DRB1*04:01.
• CP/CSP: the circumsporozoite surface
protein (CSP) and MSP: Merozoite surface
proteins (MSPs) MSP-1, MSP-3, and MSP-9
- important vaccine candidates
• Role of TNF – Cerebral malaria
susceptibility – in review – only proven role
in blocking iron absorption
Garamszegi LZ. Global distribution of malaria-resistant MHC-HLA alleles: the number and
frequencies of alleles and malaria risk. Malaria Journal. 2014;13:349. doi:10.1186/1475-
2875-13-349.
Lima-Junior J da C, Pratt-Riccio LR. Major Histocompatibility Complex and
Malaria: Focus on Plasmodium vivax Infection. Frontiers in Immunology.
2016;7:13. doi:10.3389/fimmu.2016.00013.
HLA & MALARIA

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• HLA class I Cw*6 and HLA class II DRB*10 alleles promote
viral clearance group
• The HLA class I B*38 allele : more prone for chronic
hepatitis C
• HLADRB1*11/*12 alleles and DQB1*0301 are associated
with HBV persistence but with HCV clearance worldwide.
• Consistent association of DRB1*03 and *07 is observed
with HCV susceptibility and non-responsiveness to HBV
vaccination across the population.
• HLA DR13 is protective for vertical HBV and HCV
transmission in Chinese and Italian neonates, alleles
under study
Ocal S, Selcuk H, Korkmaz M, Altun R, Yildirim AE, Akbas E. Effect of HLA on Hepatitis C
Virus Clearance and Persistence in Anti-HCV-positive End-stage Renal Disease
Patients. Saudi Journal of Gastroenterology : Official Journal of the Saudi Gastroenterology
Association. 2014;20(3):175-181. doi:10.4103/1319-3767.133007.
Singh R, Kaul R, Kaul A, Khan K. A comparative review of HLA associations with hepatitis B and C
viral infections across global populations. World Journal of Gastroenterology : WJG.
2007;13(12):1770-1787. doi:10.3748/wjg.v13.i12.1770.
HLA & HEPATITIS B & C

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Indian study : HLA-DRB1*1501 and
DQB1*0601 predisposed to sputum
positive pulmonary tuberculosis, and
DPB1*04 was preventive and epistatic to
this risk.
Amazon study : The HLA-DRB1*04 was
prevalent in patients with pulmonary TB
OR = 2.94
The subtype HLA-DRB1*04:11:01 OR =
2.23; 95% was associated with
susceptibility to pulmonary TB
while DRB1*04:07:01 OR = 0.02; to
protection.
All three subtypes - potential
immunogenetic markers
HLA & TUBERCULOSIS
Alleles of HLA-DRB1*04 Associated with Pulmonary Tuberculosis in Amazon Brazilian Population
Dhêmerson Souza de Lima, Mauricio Morishi Ogusku, Maisa Porto dos Santos, Cláudia Maria de Melo Silva,
Vanessa Alves de Almeida, …
Tuber Lung Dis. 1999;79(5):309-17.
Associations of HLA-DRB1, DQB1 and DPB1 alleles with pulmonary tuberculosis in south India.
Ravikumar M1, Dheenadhayalan V, Rajaram K, Lakshmi SS, Kumaran PP, Paramasivan CN, Balakrishnan
K, Pitchappan RM.

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MUMBAI STUDY
• Increase in HLA A2, A11, B40 and Cw7, while a decrease of A28, B12, B15
and Cw3
• Haplotypes A*1102-B*4006-Cw*1502; A*0203-B*4016-Cw*0703; A*11-
B*40 increased in multi-bacillary
NORTH INDIA STUDY
• Much stronger association of DRB1*1501 with the multibacillary form
than with the TT type of leprosy - possible role in the differential
immune response to M. leprae antigens.
HLA & LEPROSY
Lepr Rev. 2004 Mar;75(1):79-85.
HLA associations in leprosy patients from Mumbai, India.
Shankarkumar U1
Tissue Antigens. 1993 Sep;42(3):133-7.
Study of HLA class II alleles by PCR oligotyping in leprosy patients from north India.
Rani R1, Fernandez-Vina MA, Zaheer SA, Beena KR, Stastny P.

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HLA-B*57 and HLA-B*27 are associated with
improved HIV control
Association of HLA-B*35 - with worse outcome
CTL escape:
Loss of T-cell reactivity may not be directly linked to
HIV-specific CD4+ T-cell responses but that
increased viremia after CTL escape may influence
CD4+ T-helper responses.
Goulder PJR, Walker BD. HIV and HLA Class I: an evolving relationship. Immunity. 2012;37(3):426-440. doi:10.1016/j.immuni.2012.09.005
CTL escape and increased viremia irrespective of HIV-specific CD4+ T-helper responses in two HIV-infected individuals Mark J. Geels a,1, Christine A. Jansen b,d,1, Elly Baan a , Iris M. De Cuyper b , Gijs J.M. van
Schijndel b , Hanneke Schuitemaker b , Jaap Goudsmit c , Georgios Pollakis a , Frank Miedema b,d, William A. Paxton a , Debbie van Baarle b,d,*.
HLA & HIV-AIDS

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HLA TYPING

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• HLA typing along with ABO (blood type) grouping - used to evaluate tissue compatibility between a
donor and a potential transplant recipient.
• Serological typing methods or molecular typing methods: Serologic HLA typing methods detect the epitopes
of the HLA molecules, whereas the molecular methods detect the nucleotide sequences.
• HLA typing that defines groups of alleles is referred to as low-resolution or generic typing (HLA- DRBl-04).
• HLA Typing that resolve all known alleles is referred to as high-resolution HLA typing (HLA- DR BI x401).
• HLA Typing that resolves beyond serologic specificities but that does not achieve allele level is referred to as
intermediate -resolution typing (For example, HLA- DRBl-0401/09/13/16/21/26/33).
Serological:
1. Complement Dependent Cyto-toxicity (phenotyping)
2. HLA antibody screening
Molecular: (genotyping)
1. PCR amplification & sequencing
2. PCR-RFLP
3. PCR-SSO
4. PCR-SSP
5. PCR-SBT
HLA TYPING

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Isolation of Lymphocytes for HLA Typing:
i. Peripheral venous blood is mixed with Ficoll- Hypaque and centrifuged, Layer containing peripheral blood
mononuclear cells is aspirated, washed, and used
ii. Anti-CD2 or anti-CD3 mAbs coated magnetic beads are used to isolate T cells; and anti-CD19 mAbs coated
magnetic beads are used to isolate B cells.
HLA TYPING - PREPARATION

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CYTOTOXIC CROSS-MATCH - PRA
1. Set of cell donors - randomly selected to be representative of a population (representative of the
population of potential deceased donors) - 30 to 40 different donor lymphocytes.
2. Similar to that of serologic typing except - here recipient serum is mixed with “cell donor” lymphocytes in
individual wells along with complement and dye. Where the serum contains antibodies that bind to the
cell surface with adequate density complement pathways are activated which results in cell death and
uptake of the dye.
3. The degree of cytotoxicity is expressed as percentage PRA (panel reactive antibody) - tool employed to
approximate the risk of a given recipient of having a positive crossmatch
4. Limitations: PRA percent can be different numerically - depending on the cell panel used which are
commercially produced and may not truly represent the population – HENCE FALSE POSITIVE – reducing
the chances of a recipient getting a transplant just because the PRA was significant
5. CDC –crossmatch with calculated PRA using specific antigens/antibodies preferred – cytometry or beads
can be used

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1. Can be used to detect either HLA antigen or antibody based on the same concept of complement dependent
killing – Mapping*
2. Test lymphocytes/serum are incubated with known HLA antigen/antibodies (binding occurs if specific HLA
antigens/antibodies are present.)
3. Five µl complement (usually, rabbit serum) is added to each well and incubated for 60 minutes,
(complement proteins cause death of lymphocytes that are coated with mAbs. In the absence of mAb
binding with lymphocytes, the complement is not activated and the lymphocytes are not killed).
4. The dye eosin Y, followed by formaldehyde (formaldehyde fixes the reaction) are added and viewed under
an inverted/phase contrast microscope
COMPLEMENT DEPENDENT CYTO-TOXICITY

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• ELISA method is easy, fast, and doesn’t require live lymphocytes as well as complement. Affinity-purified HLA
antigens are coated on the walls of the microtiter plate.
• Recipient’s serum is added and incubated
• After washing, enzyme conjugated anti-human IgG is added and incubated
• After washing, substrate is added and incubated.
• i. Development of color in a particular well indicates the presence of IgG antibodies against the HLA antigen
coated on that particular well.
• ii. Non-development of color in a particular well indicates the absence of antibodies to the particular HLA
antigen coated on that well.
ANTIBODY SCREENING - ELISA

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1. Flow cytometer cross matching : 30-250 times more sensitive than the visual serologic methods for the
detection of IgG antibodies against HLA antigens on the surface of lymphocytes.
2. Peripheral blood lymphocytes of the proposed donor are incubated with fluorescent labeled anti-CD3 mAbs,
which bind to T cells
3. Beads (micro-particles) coated with required antigens can also be used
4. The labeled ani-CD3 bound T cells are separated from B cells in the flow cytometer and the separated,
stained T cells are now incubated with the waiting recipient’s serum.
5. Recipient’s serum antibodies against the donor T cell HLA antigens, if present, will bind to the T cells.
6. After washing, a fluorochrome (that emits a color, other than green, say red color) labeled anti-human IgG is
added and incubated.
7. The fluorochrome labeled anti-human IgG will bind to the recipient’s HLA antibodies, which are bound to the
donor T cells.
8. The flow cytometer counts the number of T cells (red and green color) and T cells (green color) and creates a
histogram.
FLOW CYTOMETRY

53. The sample is added to a mixture
of color-coded beads, pre-coated
with analyte-specific capture
antibodies. The antibodies bind to
the analytes of interest.
Biotinylated detection
antibodies specific to the
analytes of interest are added
and form an antibody-antigen
sandwich. Phycoerythrin (PE)-
conjugated streptavidin is
added. It binds to the
biotinylated detection
antibodies.
Polystyrene beads are read on a dual-laser flow-based detection instrument, such as
the Luminex® 100™, Luminex 200™ or Bio-Rad®Bio-Plex® analyzer. One laser classifies
the bead and determines the analyte that is being detected. The second laser
determines the magnitude of the PE-derived signal, which is in direct proportion to the
amount of analyte bound.
ANTIBODY SCREENING - LUMINEX BEAD ASSAY

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MOLECULAR METHODS
PCR-RFLP:
Polymerase Chain Reaction – Restriction Fragment
• PCR amplified DNA digested with restriction enzyme
to generate specific restriction pattern and alleles are
identified according to pattern.
• Can distinguish polymorphisms associated with DR3,
DR5 and DR6 haplotypes
• Long procedure and extensive handling of samples
PCR-SSO
Polymerase Chain Reaction – Sequence Specific
Oligonucleotides
• Labelled sequence specific probes are hybridized to
PCR amplified DNA and then detected.
• Most specific technique, results within 10 hours,
easier handling of several samples in one run.
• Very precise requirements in terms of temperature or
hybridization for example
PCR-SSP
Polymerase Chain Reaction – Sequence Specific
Primer
• Primers are designed with specificity-dependent
nucleotide on the 3’ end.
• Faster than PCR-RFLP and SSO, slightly cheaper
• Some equivocal results of typing of certain types
of alleles observed
PCR-SBT
Polymerase Chain Reaction – Sequence Based
Testing
• DNA amplified using PCR specific for site of
interest, products purified and then sequenced,
most specific and reliable
• Very expensive equipment

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HLA NEWER ASSOCIATIONS & CONCEPTS

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Sleep disorder associated with HLA DR15 (DR2) and
DQB1*0602.
DQB1*0602 frequency was strikingly higher in
patients with cataplexy versus patients without
cataplexy (76.1% in 421 patients versus 40.9% in 88
patients). Positivity was highest in patients with
severe cataplexy (94.8%) and progressively
decreased to 54.2% in patients with the mildest
cataplexy.
Sleep. 1997 Nov;20(11):1012-20.
HLA DQB1*0602 is associated with cataplexy in 509 narcoleptic patients.
Mignot E1, Hayduk R, Black J, Grumet FC, Guilleminault C.
HLA & NARCOLEPSY

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A significant association between C282Y and
the HLA-A3/B7 haplotype was found
Pacho A, Mancebo E, del Rey MJ, et al. HLA haplotypes associated with hemochromatosis mutations in
the Spanish population. BMC Medical Genetics. 2004;5:25. doi:10.1186/1471-2350-5-25.
HLA & HEMOCHROMATOSIS

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HLA STRIPPED PLATELETS
Platelet transfusion refractoriness is typically diagnosed using the corrected count increment, :
1. Pre-transfusion platelet count
2. Post-transfusion platelet count: (END OF 1 HOUR)
3. Body surface area
4. Number of platelets transfused (@ 3.0 x1011 platelets/unit)
CCI = (Post-transfusion platelet count - Pre-transfusion platelet count)(BSA) ÷ (number of platelets transfused).
A CCI > 7500 - sufficient post-transfusion increment, CCI < 7500 : Diagnostic of platelet refractoriness.
HLA STRIPPED PLATELETS:
Standard platelets of HLA class I using a brief incubation at low pH.
Such HLA‐stripping results in a reduction in HLA class I expression at the surface, followed by loss of reactivity to HLA
class I‐specific antibodies.

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SAVIOR SIBLING
The creation of saviour siblings using fertility treatment is now possible in the United Kingdom as a result of the
decision in Quintavalle v Human Fertilisation and Embryology Authority:
- A licence…cannot authorise the testing of an embryo, except for one or more of the following purposes:
(d) in a case where a person (‘the sibling’) who is the child of the persons whose gametes are used to bring
about the creation of the embryo (or of either of those persons) suffers from a serious medical condition which
could be treated by umbilical cord blood stem cells, bone marrow or other tissue of any resulting child,
establishing whether the tissue of any resulting child would be compatible with that of the sibling.
Britain's only saviour sibling twins
At the age of two, little do they know it but Amy and Anthony Maguire
are Britain's only 'saviour sibling' twins, created to be donors for their
sick older brother.

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Thank you