IT CONTAINS THE LATEST INFORMATION ABOUT MHC MOLECULE WHICH WILL BE HELPFUL FOR B.SC /M.SC/CSIR-NET/DBT-JRF/GATE STUDENTS. THIS IS IN VERY SIMPLE AND LUCID MANNER TO UNDERSTAND AND ONE CAN EASILY OPT FOR THIS TO PREPARE NOTES.
In class presentation for an advanced cell biology course at KSU, fall 2017. Background knowledge includes a previous immunology course, about 6 biochemistry courses and research.
Major Histocompatibility Complex (MHC) plays a cardinal role in T cell-mediated immunity. Modern immunogenetics largely depends on the research on the MHC complex.
This ppts file will give the students of biochemistry or biology, in general, a brief outlook on the structure and functions of MHC, as well as its mode of action.
I hope this work will help intermediate students grasping the topic.
IT CONTAINS THE LATEST INFORMATION ABOUT MHC MOLECULE WHICH WILL BE HELPFUL FOR B.SC /M.SC/CSIR-NET/DBT-JRF/GATE STUDENTS. THIS IS IN VERY SIMPLE AND LUCID MANNER TO UNDERSTAND AND ONE CAN EASILY OPT FOR THIS TO PREPARE NOTES.
In class presentation for an advanced cell biology course at KSU, fall 2017. Background knowledge includes a previous immunology course, about 6 biochemistry courses and research.
Major Histocompatibility Complex (MHC) plays a cardinal role in T cell-mediated immunity. Modern immunogenetics largely depends on the research on the MHC complex.
This ppts file will give the students of biochemistry or biology, in general, a brief outlook on the structure and functions of MHC, as well as its mode of action.
I hope this work will help intermediate students grasping the topic.
2. HLA human leukocyte antigens:
Alloantigen – differ among members of same species
present on surface of cells, encoded on HLA genes
Genes clustered on MHC, located on short arm of chromosome6.
HLA Genes
HLA-A, HLA-B, HLA-C → Class I MHC proteins
HLA-D → DP, DQ, DR → Class II MHC proteins
Class III Genes for → C2, C4, TNF, Lymphotoxin LT
2 haplotypes, maternal and paternal sets
Polymorphic (many alleles) HLA-A – 47, HLA-B – 88, HLA-C – 29, HLA-D - 300
3. Every person has single allele at each locus. So inherit
two haplotypes – 1 maternal on chromosome 6, 1 paternal set.
Each allele can make 2 class I & 2 class II proteins. Co- dominant. Proteins by both are expressed.
Each person can make 12 HLA proteins 3 each at class I and II loci, from both chromosomes
Minor antigens by genes at other sites. Body proteins with 1 or more different amino acid → weak immune response → slow rejection of graft.
4. Class I MHC: glycoprotein. Present on All nucleated cells
20 proteins encoded by A, 40 by B, 8 by C gene locus
45,000 Mol. wt. Heavy chain non covalently bound to β2 microglobulin. Similar to Ig molecule. Highly polymorphic. Importance is recognition of self & non self. Hypervariable region at N terminal region. constant region binds to CD 8 of cytotoxic T cell
5. Class II MHC: glycoprotein. Highly polymorphic
Present on Macrophages, B cell, Dendritic cell Spleen, Langerhans cell (skin)
Made up of 2 polypeptides (mol wt. 33000, 28000) non covalently bound. Constant region for CD4 protein of helper T cell
Functions of Major Histocompatibility Complex MHC
1. Positive selection of T cells in thymus
2. Antigen presentation
6. Present antigens to T cells which recognize antigen only if associated to self class I or II MHC → immune response - MHC restriction.
Success of organ or tissue transplant - compatibility of donor & recipient MHC genes. If HLA proteins differ → immune response → rejection of graft. Minor antigens → slow rejection.
Autoimmune diseases: occur in individuals who carry
certain MHC genes
7. Auto graft: Transfer of individuals own tissue to another site in the body. Permanently accepted
Syngeneic graft: Transfer of tissues between genetically identical individuals e.g identical twins
Xenograft: Transfer between different species.
Allograft: Transfer between members of same species. Usually rejected unless immunosuppressive drugs given e.g from one human to another.
8. Allografts are rejected by a process known as allograft reaction.
In an acute allograft reaction;
vascularization of the graft is normal initially, but in 11-14 days, marked reduction in circulation and mononuclear cell infiltration occurs, with eventual necrosis.
This is called a primary (first-set) reaction
A T-cell-mediated reaction is the main cause of rejection of many types of grafts, e.g., skin, but antibodies contribute to the rejection of certain transplants, especially bone marrow
9. If a second allograft from the same donor is applied to a sensi
The major histocompatibility complex (MHC) is a collection of genes that encode molecules of genetically diverse glycoproteins, that are found on the plasma membranes of mammalian nucleated cells.
I explain only two major classes of MHC molecules such as class one and class two of MHC.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
2. HLA human leukocyte antigens:
Alloantigen – differ among members of same species
present on surface of cells, encoded on HLA genes
Genes clustered on MHC, located on short arm of chromosome6.
HLA Genes
HLA-A, HLA-B, HLA-C → Class I MHC proteins
HLA-D → DP, DQ, DR → Class II MHC proteins
Class III Genes for → C2, C4, TNF, Lymphotoxin LT
2 haplotypes, maternal and paternal sets
Polymorphic (many alleles) HLA-A – 47, HLA-B – 88, HLA-C – 29, HLA-D - 300
3. Every person has single allele at each locus. So inherit
two haplotypes – 1 maternal on chromosome 6, 1 paternal set.
Each allele can make 2 class I & 2 class II proteins. Co- dominant. Proteins by both are expressed.
Each person can make 12 HLA proteins 3 each at class I and II loci, from both chromosomes
Minor antigens by genes at other sites. Body proteins with 1 or more different amino acid → weak immune response → slow rejection of graft.
4. Class I MHC: glycoprotein. Present on All nucleated cells
20 proteins encoded by A, 40 by B, 8 by C gene locus
45,000 Mol. wt. Heavy chain non covalently bound to β2 microglobulin. Similar to Ig molecule. Highly polymorphic. Importance is recognition of self & non self. Hypervariable region at N terminal region. constant region binds to CD 8 of cytotoxic T cell
5. Class II MHC: glycoprotein. Highly polymorphic
Present on Macrophages, B cell, Dendritic cell Spleen, Langerhans cell (skin)
Made up of 2 polypeptides (mol wt. 33000, 28000) non covalently bound. Constant region for CD4 protein of helper T cell
Functions of Major Histocompatibility Complex MHC
1. Positive selection of T cells in thymus
2. Antigen presentation
6. Present antigens to T cells which recognize antigen only if associated to self class I or II MHC → immune response - MHC restriction.
Success of organ or tissue transplant - compatibility of donor & recipient MHC genes. If HLA proteins differ → immune response → rejection of graft. Minor antigens → slow rejection.
Autoimmune diseases: occur in individuals who carry
certain MHC genes
7. Auto graft: Transfer of individuals own tissue to another site in the body. Permanently accepted
Syngeneic graft: Transfer of tissues between genetically identical individuals e.g identical twins
Xenograft: Transfer between different species.
Allograft: Transfer between members of same species. Usually rejected unless immunosuppressive drugs given e.g from one human to another.
8. Allografts are rejected by a process known as allograft reaction.
In an acute allograft reaction;
vascularization of the graft is normal initially, but in 11-14 days, marked reduction in circulation and mononuclear cell infiltration occurs, with eventual necrosis.
This is called a primary (first-set) reaction
A T-cell-mediated reaction is the main cause of rejection of many types of grafts, e.g., skin, but antibodies contribute to the rejection of certain transplants, especially bone marrow
9. If a second allograft from the same donor is applied to a sensi
The major histocompatibility complex (MHC) is a collection of genes that encode molecules of genetically diverse glycoproteins, that are found on the plasma membranes of mammalian nucleated cells.
I explain only two major classes of MHC molecules such as class one and class two of MHC.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
3. • Difficulty during transplantation…rejection
• Immune responses: antibody formation, TH, CTL
• Highly polymorphic √
• Bind peptide…….. recognized by T cells
3
4. • Are self antigen (autoantigen)
• Found on all cells of nucleated humans and all
vertebrates cells
• Discovered during transplantation experiment in mice
– Transplanted organ is accepted sometimes (genetically the
same) and rejected some other time (genetically different)
– The answer was given by George Snell: the tissue of donor and
recipient are incompatible
– Closely related gene: Major histocompatibility complex (MHC)
4
5. MHC Genes
The human MHC genome is called HLA (Human
Leukocyte Antigen-HLA)….tightly linked cluster of genes
The mouse MHC genome is H-2.
• MHC class I = HLA-A, HLA-B & HLA-C
• MHC class II = HLA-DP, HLA-DQ, &HLA-DR (D region)
• MHC class III = Complement factors C2, C4,&
Factor B
• Genes encoding in this MHC III do not play any
role in antigen presentation.
5
6. MHC is Polygenic and Polymorphic
It is polygenic because it has several genes for each
class (3 for class-I, 6 for class-II).
It is polymorphic due to the relatively large number
of alleles within each MHC class within the species.
6
9. Importance of MHC polymorphism
• Polymorphism and polygeny
– is the generation of a highly diverse repertoire of
MHC molecules capable of presenting a large variety
of Ag peptides to T cells
9
10. MHC gene inheritance to offspring
• Most individuals are heterozygous in terms of MHC
inheritance.
• For each MHC genes every individual inherits one
MHC allele from each parent, maternal and paternal.
• The MHC molecules are expressed co-dominantly
• In any mating, four possible combinations of
haplotypes can be found in the progenies, for each
MHC gene.
10
11. Classification and structure of MHC
• 2 types of polymorphic genes, the class I and II
encodes two groups of structurally distinct but
homologous proteins.
• MHC class-I is made up of two polypeptide
chains: One large called and one small called
2 microglobulin, it is not polymorphic.
• The chain has 3 extracellular domains (1, 2
& 3), a transmembrane and a cytoplasmic
segment. 11
12. The 1 and 2 domains form a cleft where the
Ag fragment of antigen binds.
The 2 microglobulin has only one
extracellular domain
No transmembrane portion
No cytoplasmic tail
Immunoglobulin-like region: highly
conserved α3 domain - site to which CD8 on T
cell binds 12
15. MHC Class-II molecules
o Composed of two polypeptide chains and .
o Each chain has two extracellular domains 1 2
and 1 and 2
o A transmembrane segment
o A cytoplasmic tail
o The 1 and 1 domains form the cleft for the Ag
fragment
oImmunoglobulin-like region – conserved α2 and β2
domains – β2 is site to which CD4 on T cell binds 15
19. Class I or II MHC: Interaction with Peptides
• Has a broad specificity
• Has a single peptide binding cleft
• The peptide sequences that bind to MHC molecules are
distinct from those recognized by T cells
• The affinity of peptide-MHC interactions is much lower
than that of antigen-antibody binding
• Peptide-MHC complexes persist long due to low rate of
Dissociation
• MHC molecules don’t discriminate between self and non
Self antigens
19
20. Genomic of MHC molecules
In Humans, MHC is located on the short arm of
chromosome 6 and -2 Microglobulin is encoded by a gene
on chromosome 15
MHC of human occupies ~3500kb
• MHC-I are in the most telomeric region and MHC-II
are in the most centromeric region of HLA locus
• Other genes in the class II locus
-TAP 1 and 2
- subunits of a cytosolic protease complex (Proteasome)
- HLA-DM
20
22. •MHC class III = Between class I and II gene
• Complement factors C2, C4,& Factor B
• Genes encoding in this MHC III do not play
any role in antigen presentation
22
23. Expression of MHC molecules
• MHC-I expressed on all nucleated cells
• MHC-II expressed on APCs: Macrophages, B cells and Dendritic cells
• Expression of MHC molecules is increased by cytokines!!
produced during innate and adaptive immune responses
Interferon , , , Tumor necrosis factor (TNF) and
lymphotoxin increases expression of class I molecules
Interferon : stimulates expression of class II molecules??
23
26. Both of them have a peptide-binding groove with a
wall of 2 α helices and a floor of 8 β-pleated sheets
Close-ended groove for class I MHC requires an 8-10
amino acid-length peptide to bind
Open-ended groove for Class II MHC lets it bind a
peptide 13-25 amino acids long
Peptide-binding site for MHC-I and MHC-II are
structurally similar
26
28. Properties of MHC
o are membrane-bound, recognition by T cells
requires cell-cell contact.
o Peptide/antigen from cytosol attach to class
I MHC and is recognized by CD8+ cells.
o Peptide from vesicles associates with class
II MHC and is recognized by CD4 cells.
28
29. o Though there is a high degree of polymorphism
(MCH) for a species, an individual has maximum
of six different class I MHC products and maybe
more class II MHC products (12).
o Antigen must associate with a given MHC of that
individual, otherwise no immune response can
occur.
29
30. o Mature T cells must have a T cell receptor that
recognizes the peptide associated with self MHC
.
o Each MHC molecule has only one binding site
o Different peptide/antigen can bind a given MHC
molecule, degenerate
o All bind to the same site, but only one at a time.
30
31. o MHC polymorphism is determined at germline.
There is no recombinational mechanism for
generating diversity
o Cytokines increase level of expression of MHC.
o `controlled by transcription factors
o Alleles for MHC genes are co-dominant. Each
MHC gene product is expressed on the cell
surface of an individual nucleated cell.
31
32. MHC & Immune responsiveness
• The MHC polymorphism within a species will generate a
diversity of binding specificities, and thus different
patterns of responsiveness to antigens.
• The absence of an MHC molecule that can bind and
present a given peptide, or the absence of T-cell
receptors that can recognize a given peptide–MHC
molecule complex, could result in the absence of
immune responsiveness.
• Some HLA alleles occur at a much higher frequency in
those suffering from certain diseases than in the general
population: autoimmune disorders, certain viral diseases,
disorders of the complement system, some neurologic
disorders, and several different allergies.
32