Memory and anergy: challenges to traditional models of T lymphocyte differentiation.
Traditional paradigms suggest that encounter with an antigen converts naive peripheral T cells into memory cells with less stringent requirements for activation and increased capacities for lymphokine production. Recent evidence argues that this view may be over-simplified in two ways. First, an encounter with antigen in the absence of certain costimulatory factors can render a T cell anergic--that is, unable to respond to antigen under normal conditions. Second, although cells of the memory T cell population are more responsive than naive cells to some stimuli, these cells are hyporesponsive in other situations. Intrinsic resistance of memory T cells to elevation of intracellular calcium ion concentrations may contribute to their poor responsiveness to agents that activate naive cells. Thus, aspects of the costimulatory environment can determine whether a resting T cell is activated or rendered anergic and may also influence the kinds of stimuli to which a memory T cell will respond.
Jenkins
M K
MK
Department of Microbiology, University of Minnesota, Minneapolis 55455.
Miller
R A
RA
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology; D002454:Cell Differentiation; D006801:Humans; D007156:Immunologic Memory; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
D015703:Antigens, CD