Dr Ambika Jawalkar
Dr Ambika Jawalkar
Architecture of Immune System
1. Mononuclear-Phagocytic System (MPS)
2. Lymphoid Component
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
Hematopoietic stem cell
Committed stem cell
Monoblast
Promonocyte
Monocyte
Macrophage
GM –CSF
GM –CSFG –CSFSCFIL – 1, 3, 6
M - CSF
M - CSF
BONE MARROW
BLOOD
TISSUES
CENTRAL MONOCYTE POOL
MARGINAL MONOCYTE POOL
DIAPEDESIS
CHEMOTAXIS
FIXED MACROPHAGES MOBILE MACROPHAGES
TRANSFORMATION DIFFERENTIATION
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.
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
Definition - Process of engulfment and destruction of particulate material by the cells
Also called cell eating
Phagocytes - NeutrophilsMonocytesFixed tissue macrophages
STEPS1.Margination2.Diapedesis3.Chemotaxis4.Opsonisation5.Engulfment6.Degranulation7.Degradation or killing - O2 dependent
O2 independent
MARGINATION: Vasodilation- histamine, serotonin, bradykinin, NO Neutrophils get attached towards the capillary
endothelium - endothelial selectinsintegrins on neutrophilsICAM & VCAM
DIAPEDESIS: Insinuation of neutrophils through capillary walls
CHEMOTAXIS:
Neutrophils are attracted towards bacteria at the site of inflammation
Chemotactic agents are-C5aLeukotriene B4CytokinesIL-8
OPSONIZATION:
Coating of bacteria by opsonins - IgGC3b
ENGULFMENT:By forming phagocytic vesicle
DEGRANULATION:
DEGRADATION:I. O2 independent mechanism:
-through lysosomal enzymes
II. O2 dependent mechanism:NADPH + H+ + 2O2 NADP+ + 2H+ + 2O2
-
O2- + O2
- + H+ + H+ H2 O2 + O2
Cl -,Br - HOCl, HOBr
LYMPHOID ORGANS
Central / Primary :* Thymus* Bursa Equivalent
Peripheral :* Lymph nodes* Spleen* MALT
IMMUNITY
INNATE
NON-SPECIFIC
SPECIFIC
-Species
- Racial
-Individual
ACQUIRED
ACTIVE
Natural Artificial
PASSIVE
Natural Artificial