1. The document discusses the immune system, including its two main arms - innate and adaptive immunity. It describes key cells involved like macrophages, neutrophils, dendritic cells, NK cells, B cells, T cells and their roles. 2. Important concepts covered include the adaptive immune system producing long-lasting active immunity through antibodies and memory cells. Innate immunity provides immediate but non-specific responses. 3. The roles and characteristics of the major classes of antibodies (IgG, IgA, IgM, IgE, IgD) are defined. The document also examines antigens, antigen presentation through MHC molecules, and the complement system.

1. COURSE CODE: 301
Dr. UZMA NAZ

2. HEMODYNAMIC DISORDERS
EMBOLISM
INFARCTION
SHOCK

4. IMMUNITY
• Greek word
Immunis:- Free from burden
Sequence of cellular and molecular events
designed to rid the host of an offending
stimulus
Pathogenic organismtoxic substancescellular
debris neoplastic cells

5. IMMUNOLOGY
• Science which deals with the body’s
response to antigenic challenge.
• Deals with the vital immune system.
• Immune system is an interacting set of
specialized cells and proteins designed to
identify and destroy foreign invaders or
abnormal substances before they damage
the body.

6. TWO ARMS OF IMMUNE SYSTEM
1.INNATE (OR NATURAL) IMMUNE SYSTEM
A. NON SPECIFIC
– Physical barrier: skin, mucus
– Proteins in serum and in tissues: Lysozyme, interferon,
complements. (eg. In tears…….)
B. SPECIFIC
– Antibody mediated
– Cell mediated
2.ADAPTIVE(OR ACQUIRED)SPECIFIC
IMMUNE SYSTEM

8. Active Passive
1.Produced actively by the
immune system of host
1.Received passively by the host and the
immune system doesn’t participate.
2.Induced by infection or by
contact with immunogen.
2.Conferred by introducing ready made
antibody.
3. Immune response-durable
and effective
3. Immune response-short lived and less
effective
4.Immunity develops only
after a long period.
4.Immunity effective immediately.
5.Immunological memory
presumed.
5.No immunological memory.
6.Serves no purpose in
immunodeficient host.
6.Applicable in immuno-deficient host.
7.No inheritance of
immunity.
7.May be acquired from mother

10. Innate Immunity
• Components :
 Macrophages
 Granulocytes
 Natural killer cells
 Complement
 Other chemicals eg. HCl, Lysozymes
• Characteristics:
 Immediate action
 Non-specific response

11. Adaptive Immunity
• Humoral
– B cells
– Antibodies
– Complements
• Cell-mediated
– Antigen Presenting Cells
– T cells
Characteristics:
Specific response
Late response

13. CELLS OF THE IMMUNE SYSTEM
• LYMPHOCYTES, T
• LYMPHOCYTES, B
• PLASMA CELLS (modified B cells)
• MACROPHAGES (“HISTIOCYTES”)
–Antigen Presenting Cells (APCs)
• “DENDRITIC” CELLS
–Antigen Presenting Cells (APCs)
• NK (NATURAL KILLER) CELLS

14. CELLS OF IMMUNE SYSTEM
• T-Lymphocytes
–Thymus derived lymphocytes
–Role in cellular or cell-mediated
immunity.
–Constitutes 60-70% of peripheral
lymphocytes
–Differentiation of T-cells

15. Helper T cells
–CD 4 Cells
–Essential to the differentiation of B-cells
into plasma cells and their subsequent
secretion of Antibodies.
–Each helper T-cell is capable of activating
hundreds of specific B-cells

16. SUPPRESSOR T-CELLS :
• CD 8 Cells
• inhibit the development of B-cells in to plasma
cells
• regulate the activity of killer T-cells and
• suppress the production of Abs when they
become excessive.
• Also suppress auto-immune responses.

17. KILLER T-CELLS
• CD 8 Cells
• Have specific receptor for antigenic determinants.
• Killer T-cell migrate from lymphoid tissue to the site of
foreign cell invasion where they secrete small protein,
lymphokines.
• Prevent the reproduction of invading micro-organisms,
infected host cells or viruses inside host cells.

18. MEMORY T-CELLS
• The T-cells that remain potentially active and
viable even after the antigen has been
inactivated.
• Upon 2nd encounter memory cells proliferate,
differentiate into plasma cells and secrete Abs so
rapidly that the symptoms of the disease may not
even be observed.

19. CELLS OF THE IMMUNE SYSTEM
Cell Type Derivation Location Function
T cells
CD4 (helper)
CD8
(cytotoxic
/suppressor)
Bone marrow
lymphocyte
stem cells mature in
thymus
Peripheral blood and bone
marrow, thymus,
paracortex of lymph
nodes, Peyer's patches
CD4 cells: secrete cytokines (IL-2 →
proliferation of CD4/CD8 T cells; γ-interferon
→ activation of macrophages); help B cells
become antibody-producing plasma cells
CD8 cells: kill virus-infected, neoplastic, and
donor graft cells
B cells Bone marrow stem
cells
Peripheral blood and bone
marrow, germinal follicles
in lymph nodes, Peyer's
patches
Differentiate into plasma cells that produce
immunoglobulins to kill encapsulated bacteria
(e.g., Streptococcus pneumoniae)
Act as APCs that interact with CD4 cells
Natural killer
cells
Bone marrow stem
cells
Peripheral blood (large
granular lymphocytes)
Kill virus-infected and neoplastic cells
Macrophages Conversion of
monocytes into
macrophages in
connective tissue
Connective tissue; organs
(e.g., alveolar macrophages,
lymph node sinuses)
Involved in phagocytosis and cytokine
Production
Act as APCs
Dendritic cells Bone marrow stem
cells
Skin (Langerhans' cells),
germinal follicles
Act as APCs

20. L
Y
M
P
H
S

21. 1) ROUND NUCLEUS
2) OVOID CYTOPLASM
3) PERIPHERAL CHROMATIN
4) “CLEAR ZONE” BETWEEN NUCLEUS AND WIDER LIP OF
CYTOPLASM
PLASMA CELLS

22. MACROPHAGES are
MONOCYTES that have come
out of circulation and have
gone into tissue

23. Dendritic cells
• A type of macrophage
with many spiny
cytoplasmic
processes, found in
many places
– skin (Langhans cells)
– brain (microglia)
• They are also APC’s.

24. • Humoral immunity • Cellular immunity
24
Types of Immunity

25. Antigens
 Basically Exogenous
 Occasionally may be derived from body’s own tissues
 Protein molecules or part which have specific AA sequence
folded in tertiary shapes.
 Substances that stimulate Ab production when they react.
 Molecular wt. : 8000 or more

26. ANTIBODY
o Specific glycoprotein molecules generated by B –
cells in response to antigens.
o Also called immunoglobulins.
o Humoral substance found in serum,lymphs and
other body fluids.
o Highly specific in nature.

27. FUNCTIONS
• Neutralization of toxins.
• Activation of complement (results in improved
opsonisation)
• Lysis of invading microorganisms.

28. ORGANS PRODUCING ANTIBODIES
• Spleen, lymph nodes and bone marrow
• Tissues like peyer’s patches, appendix,
thymus
• These structures contains lymphocytes
macrophages and plasma cells

29. IMMUNOGLOBULIN
• Immunoglobulins are synthesized by plasma cells
and also by lymphocytes.
• All antibodies are Immunoglobulins but all
Immunoglobulins may not be antibodies.

30. Classification:
Types based on Size, Carbohydrate content
and amino acid analysis:
• IgG
• IgM
• IgA
• IgD
• IgE

31. IMMUNOGLOBULIN
IgG:
– comprises 70% of total Ig.
– Shortest half life of 21 days
– Lowest mol. Wt. and found in highest concn in
body.
– crosses placenta and provides much of maternal
antibody.
– Responsible for late immune response.

32. IgA:
•In body secretion like milk, tears, saliva, urine
etc.
•Also called secretory immunoglobulins
•Antibacterial and antiviral
•Majorly generated in bone marrow

33. IgM
–Highest mol.wt
–Present in serum as pentamer
–Constitute only 10% of serum
immunoglobin
–Can’t cross transplacental barrier.
–Responsible for early immune response.

34. IgE:
– Play role in parasitic and allergic disease.
– Shortest half life.
– Present in small quantities.
IgD:
– Present in the surface of the lymphocytes.
– Least abundant of all.
– Mainly intravascular distribution.

36. MHC
MAJOR HISTOCOMPATIBILITY COMPLEX
• A genetic “LOCUS” on Chromosome 6, which codes
for cell surface compatibility
• Also called HLA (Human Leukocyte Antigens) in
humans and H-2 in mice
• It’s major job is to make sure all self cell antigens
are recognized and “tolerated”, because the general
rule of the immune system is that all UN-recognized
cells will NOT be tolerated

37. MAJOR HISTOCOMPATIBILITY COMPLEX
(MHC)
• LOCATION
– Short arm of chromosome 6
• HUMAN LEUKOCYTE ANTIGEN (HLA) GENES
– Code for HLA proteins that are unique to each
individual
• HLA ASSOCIATION WITH DISEASE
– HLA-B27 with ankylosing spondylitis
– HLA-DR2 with multiple sclerosis
– HLA-DR3 and -DR4 with type 1 diabetes mellitus

38. CLASS I MHC MOLECULES
• Coded by HLA-A, -B, and -C genes
• Present on the membranes of all nucleated cells
– Not present on mature RBCs; present on platelets
• Recognized by CD8 T cells and natural killer cells
CLASS II MHC MOLECULES
• Coded by HLA-DP, -DQ, and -DR genes
• Present on antigen-presenting cells (APCs)
– B cells, macrophages, dendritic cells
• Recognized by CD4 T cells

39. MHC MOLECULES
(Gene Products)
•I(All nucleated cells and platelets), cell surface
glycoproteins, ANTIGENS
•II(APC’s, i.e., macrophages and dendritics,
lymphs), cell surface glycoproteins, ANTIGENS
•IIIComplement System Proteins