the idiot's guide.

cell mediated immune response

Cell type	Functions and properties
Helper T cells	Involved in the cell-mediated immune response Recognises antigens presented by Class II MHC molecules Expresses CD4 Also expresses CD3, TCR & CD28 Major source of IL-2 Mediates acute and chronic organ rejection
Cytotoxic T cells	Involved in the cell-mediated immune response Recognises antigens presented by MHC class I molecules Induce apoptosis in virally infected and tumour cells Expresses CD8 Also expresses CD3, TCR Mediates acute and chronic organ rejection

basophil

Releases histamine during allergic response
Activated by C3a, C5 (Complement system)
Granules contain histamine and heparin
Expresses IgE receptors on the cell surface
- when antigen binds with IgE attached to basophil or mast cell, causes rupture of basophil
Bi-lobed nucleus

humoral immune response

B cells

10-20% of circulating lymphocytes
Acts as an antigen presenting cell
Mediates hyperacute organ rejection
Target cell for Epstein-Barr infection!
ingests protein antigens into vesicles, degrade them, and display peptides bound to MHC molecules for recognition by helper T cells
Pathology: most commonly implicated in Acute lymphoblastic leukaemia (immature B cells); Burkitt (mature B cells)

Cell type	Role
Plasma cells	Differentiated from B cells upon activation Produces large amounts of antibody specific to a particular antigen lifespan 1-2 weeks