physiology of immunity

1. Dr Ambika Jawalkar

2. Architecture of Immune System
1. Mononuclear-Phagocytic System
(MPS)
2. Lymphoid Component

3.  Also called Monocyte Macrophage system
 Commonly known as Reticulo Endothelial
system
 It is second line defense system of the body
 Phylogenetically this system is very primitive,
no animal can live with out this system
 This system is very effective in host protection
even in the absence of B / T lymphocytes
 Embryological hematopoietic stem cells derive
from ventral mesoderm of the yolk sac
 First mononuclear phagocyte appear on 12day
of gestation in the liver

4. Hematopoietic stem cell
Committed stem cell
Monoblast
Promonocyte
Monocyte
Macrophage
GM – CSF
G – CSF
SCF
IL – 1, 3, 6
GM – CSF
M - CSF
M - CSF
BONE MARROW
BLOOD
TISSUES

5. CENTRAL MONOCYTE POOL
MARGINAL MONOCYTE POOL
DIAPEDESIS
CHEMOTAXIS
TRANSFORMATION
DIFFERENTIATION
FIXED MACROPHAGES MOBILE MACROPHAGES

7. Different sites of distribution:
- Liver [Kupffer cells]
- CNS [Microglial cells]
- Connective tissue [Histiocytes]
- Lung [Dust cells]
- Skin [Langerhan cells]
- Bone [Osteoclasts]
- Kidney [Mesangial cells]
- Spleen
- Lymph node
- viscera etc.

8. FUNCTIONS OF MPS
- Phagocytosis
- Antigen presentation
- Antimicrobial activity
- Antitumor activity
- Angiogenesis
- proteolytic / inhibitor activity
- cytokine, growth factor production
- role in inflammation
- role in iron metabolism
- storage function

9.  Definition - Process of engulfment and
destruction of particulate material by the
cells
 Also called cell eating
 Phagocytes - Neutrophils
Monocytes
Fixed tissue macrophages

10. STEPS
1.Margination
2.Diapedesis
3.Chemotaxis
4.Opsonisation
5.Engulfment
6.Degranulation
7.Degradation or killing - O2 dependent
O2 independent

11.  MARGINATION:
 Vasodilation- histamine, serotonin, bradykinin, NO
 Neutrophils get attached towards the capillary
endothelium - endothelial selectins
integrins on neutrophils
ICAM & VCAM
 DIAPEDESIS:
 Insinuation of neutrophils through capillary walls

13. CHEMOTAXIS:
 Neutrophils are attracted towards bacteria at the
site of inflammation
 Chemotactic agents are-
C5a
Leukotriene B4
Cytokines
IL-8

15. OPSONIZATION:
 Coating of bacteria by opsonins - IgG
C3b
ENGULFMENT:
By forming phagocytic vesicle
DEGRANULATION:

17. DEGRADATION:
I. O2 independent mechanism:
-through lysosomal enzymes
II. O2 dependent mechanism:
NADPH + H+ + 2O2 NADP+ + 2H+ + 2O2
-
O2
- + O2
- + H+ + H+ H2O2 + O2
Cl -,Br - HOCl, HOBr

18. LYMPHOID
ORGANS
Central / Primary :
* Thymus
* Bursa Equivalent
Peripheral :
* Lymph nodes
* Spleen
* MALT

20. IMMUNITY
INNATE
NON-SPECIFIC
SPECIFIC
-Species
- Racial
-Individual
ACQUIRED
ACTIVE
Natural Artificial
PASSIVE
Natural Artificial