Overview of immune system Flashcards
Define Immune system
a complex system imp for:
1) distinguishing between self and non self
2) protecting body from foreign substances
Good Roles of the Immune System
- Defence against infections
- Defence against tumours
- clearance of cells and Tissue repair
“Foe” roles of the immune system
- injure cells + inducen pathogen inflammation
- rejects tissue grafts + newly introduced proteins
The immune response sequence
Recognition–> activation (processing) –> elimination
Biological roles of “innate” immunity
- deals with mild infections
- first phase for more serious infections
- initiates adaptive response
Biological roles of Adaptive Immunity
- specificity
- deals with stronger + more intense infections
- stronger exposure after exposure to the same antigen (memory)
Difference in response time between the two systems
Innate -> no time delay
adaptive -> delay (5-10days)
difference in diversity between the two systems
innate -> recognises larger, common features
adaptive -> recognises unique part of microbes
difference in receptor genes between the two systems
innate -> encoded in our genome
adaptive -> V(D)J recombination (clone-specific)
difference in Ligand between the two systems?
innate -> PAMPS (pathogen associated molecular patterns)
adaptive -> antigen (specifically Epitope)
difference in Memory between the two systems?
innate -> NO memory (same response after a repeated exposure)
adaptive -> memory (more intense response after repeated exposure)
Cellular components of Innate Immunity
Cellular:
- PHAGOCYTES:
- granulocytes
- monocytes
- macrophages
- dendritic cells
-NATURAL KILLER CELLS
Humoral components of Innate Immunity
- Complement system
- cytokines
- Antimicrobial peptides
Cellular components of Adaptive Immunity
Lymphocytes
Humoral components of Adaptive Immunity
- Antibodies
- cytokines released by lymphocytes
Types of Leukocytes in the peripheral blood?
Granulocytes:
- Neutrophils (65%)
- Eosinophils (2-4%)
- Basophils (1%)
Lymphocytes
monocytes (4-8%)
Steps in leukocyte migration?
1) Rolling
2) Tight Binding
3) Diapedesis
4) Migration
Rolling
- Rolling of cell on the endothelium
- Mediated by SELECTINS.
- Ligands: Carbohydrates
E-selectins -> on the endothelium
L-selectins -> on the leukocytes
P-selectins -> on the platlets + endothelial cells
Tight Binding
- mediated by INTEGRINS (found on the effector cell)
- Integrins –> Heterodimer (alpha and beta subunit)*
- Ligand: peptides (ICAM)
- conformational change occurs, increasing the strength of the binding, so stabilises the leukocyte.
Diapedesis
- This is the transendothelial transport
- also INTEGRIN mediated
Migration
Movement of Leukocyte to infection site.
- mediated by 1) chemokines 2) chemoattractants (microbial derived peptides)
- GPCR involved
Effector responses of the leukocytes
Neutrophils:
-Phagocytosis + killing
Helper T - cell:
- production of cytokines
Cytotoxic T-Cell:
-cytotoxicity
