The privacy of T cell memory to viruses.
T cell responses to viral infections can mediate either protective immunity or damaging immunopathology. Viral infections induce the proliferation of T cells specific for viral antigens and cause a loss in the number of T cells with other specificities. In immunologically naive hosts, viruses will induce T cell responses that, dependent on the MHC, recognize a distinct hierarchy of virus-encoded T cell epitopes. This hierarchy can change if the host has previously encountered another pathogen that elicited a memory pool ofT cells specific to a cross-reactive epitope. This heterologous immunity can deviate the normal immune response and result in either beneficial or harmful effects on the host. Each host has a unique T cell repertoire caused by the random DNA rearrangement that created it, so the specific T cells that create the epitope hierarchy differ between individuals. This "private specificity" seems of little significance in the T cell response of a naive host to infection, but it is of profound importance under conditions of heterologous immunity, where a small subset of a cross-reactive memory pool may expand and dominate a response. Examples are given of how the private specificities of immune responses under conditions of heterologous immunity influence the pathogenesis of murine and human viral infections.
Welsh
R M
RM
Department of Pathology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA. raymond.welsh@umassmed.edu
Kim
S K
SK
Cornberg
M
M
Clute
S C
SC
Selin
L K
LK
Naumov
Y N
YN
D000818:Animals; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006801:Humans; D007110:Immunity, Active; D007111:Immunity, Cellular; D007113:Immunity, Innate / Q000276:immunology; D007156:Immunologic Memory; D051379:Mice; D013045:Species Specificity; D013601:T-Lymphocytes / Q000276:immunology*; D014777:Virus Diseases / Q000276:immunology*
D018984:Epitopes, T-Lymphocyte