DR Medhat MRCP

Some plasma proteins with important functions in innate immunity:
Protein Target pathogen Effector mechanism
Complement C3
- Binding carbohydrates &
other molecules On bact.
Surface
- Opsonisation
- Complement ++
- Cell lysis
Serum Amyloid P
- Bacterial wall carbohydrates - Opsonisation
component
C-Reactive protein (CRP) - Bacterial wall
polysacharides
- Opsonisation
- Complement ++
Mannose-binding lectin - Glycoproteins with high - Complement ++
mannose content
Lysozyme
- Bacterial wall peptidoglycans - Cell wall digestion
Soluble CD14 - Lipopolysacharides - Inhibit lipopolysaccharides
B) Antigen presentation to the adaptive immunity :
- The antigen of the pathogen is presented to the cells of adaptive immunity (T & B
cells) via protein receptors on the surface of APCs called major histo-compatibility
complex(MHC){present in all vertebrates & its human version is called human
leucocytic antigen (HLA)}.
- MHC (HLA) are of 3 classes I,II &III classes .
- Since MHC (HLA) are proteins , so, there are encoded by genes present on MHC
(HLA) area on chromosome 6.
- MHC class I on the surface of infected cell or APC present the antigen to the
cytotoxicT-cell (also called CD8-positive T-cell) to be destroyed while MHC class II
on the surface of APC present the antigen to T-helper cell (also called CD4 positive
T-cell).