T cell memory: a role for MHC class II molecules on T cells?
A proportion of human T cells express MHC class II molecules. In this paper, the hypothesis is advanced that these MHC class II molecules present antigenic peptides acquired from interaction with other antigen-presenting cells (e.g. during the primary response) and can therefore interact in a cognitive manner with T cells with the same specificity. Memory is maintained in the physical form as clusters of T cells expressing T cell receptors and the cognate peptide-MHC class II complex; by virtue of their cognate interaction with each other these cells turn over gradually and return to the cluster when they recirculate. When fresh antigen is introduced, it is presented to some of these T cells by non-T antigen-presenting cells that provide a second signal leading to vigorous activation of the T cell. The proximity and cognate interaction of other T cells of the same specificity allows a chain reaction to occur, leading to rapid development of the secondary response. The hypothesis, which is testable, is proposed because of doubts concerning the current concept of memory as applied to T cells, and a need to understand the consequences of the expression of MHC class II molecules by a subset of T cells.
Zola
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Flinders Medical Centre, Adelaide, Australia.
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D013601:T-Lymphocytes / Q000276:immunology*
D000949:Histocompatibility Antigens Class II