Th2-cell dependent response
B cells occupy a unique position in immune responses because they express immunoglobulin (Ig) and class II MHC molecules on their cell surface. Therefore they are capable of producing antibody having the same specificity as that expressed by their immunoglobulin receptor; in addition they can function as an antigen-presenting cell. Proteins bind to the IgM receptor and will undergo endocytosis to be processed by the B cell.
This complex is recognized by the activated TH2 cell, which then secretes TGF-β, interleukin 4, 5, and 6. These cause the B cell to differentiate and express IgG molecules. The B cells mature in the lymphoid follicles where only the cells with very high affinity IgG molecules become plasma cells. These high affinity IgG molecules mediate opsonic activity and complement-mediated cytotoxic activity.
(Text taken from “the immune system”, Parham, Garland Publishing 2000 page 142,143.)
Hib vaccination results in:
Extra info: Hib vaccination has lead to a dramatic drop in the incidence of H. influenza induced meningitis in the children over 15 months due to the high efficacy rate provided to those that are immunized.
Which one of the following sets of conditions must be met to stimulate a T-helper 2 (TH2) cell to provide "help" to the cell that needs that help?