Icm. Maclennan et al., THE CHANGING PREFERENCE OF T-CELL AND B-CELL FOR PARTNERS AS T-DEPENDENT ANTIBODY-RESPONSES DEVELOP, Immunological reviews, 156, 1997, pp. 53-66
Recirculating virgin CD4(+) T cells spend their life migrating between
the T zones of secondary lymphoid tissues where they screen the surfa
ce of interdigitating dendritic cells. T-cell priming starts when proc
essed peptides or superantigen associated with class II MHC molecules
are recognised. Those primed T cells that remain within the lymphoid t
issue move to the outer T zone, where they interact with B cells that
have taken up and processed antigen. Cognate interaction between these
cells initiates immunoglobulin (Ig) class switch-recombination and pr
oliferation of both B and T cells; much of this growth occurs outside
the T zones. B cells migrate to follicles, where they form germinal ce
ntres, and to extrafollicular sites of B-cell growth, where they diffe
rentiate into mainly short-lived plasma cells. T cells do not move to
the extrafollicular foci, but to the follicles; there they proliferate
and are subsequently involved in the selection of B cells that have m
utated their Ig variable-region genes. During primary antibody respons
es T-cell proliferation in follicles produces many times the peak numb
er of T cells found in that site; a substantial proportion of the CD4(
+) memory T-cell pool may originate from growth in follicles.