CD4 T–cell memory can persist in the absence of class II

Abstract

To understand how memory CD4 T cells are generated we have re–examined the requirements for continuing antigen stimulation in the generation and persistence of this population. We find that specific antigen is only required for a short period during the activation of naive CD4 Tcells and is not required for memory generation from activated CD4 T cells or for persistence of resting memory cells generated by transfer of activated CD4 to adoptive hosts. Moreover, transfer of activated CD4 T cells to class–II–deficient hosts, indicates that T cR–class II major histocompatibility interaction is also unnecessary for either the transition from activated CD4 T cell to resting memory cells or for persistence over an eightweek period. Thus the signals regulating generation and maintenance of memory are fundamentally different from those which regulate the expansion of effector CD4 T–cell populations which include antigen itself and the CD4 T–cell autocrine cytokines induced by antigen.