Macaque CD4+ T-cell subsets: influence of activation on infection by simian immunodeficiency viruses (SIV).
Simian immunodeficiency virus (SIV) infects a small number of CD4+ T cells including "memory" T cells. The following describes the cell surface markers which may delineate subsets of CD4+ memory T cells and reviews how memory CD4+ T cells are activated and regulated through the T-cell receptor and such accessory receptors as CD28. The factors which may influence initial expression and infection of T cells by CD4 are discussed. Unlike activated and infected T cells, unstimulated CD4+ T cells have little or no SIV DNA detectable in the genomic fraction, but key activation signals may promote integration of viral DNA in memory T cells. Bacterial superantigens (SuperAg) can promote increased levels of SIV viral DNA in mature and immature T cells. Immunodeficiency virus products such as gp120, Nef, and Tat can affect CD4+ T-cell function. Whereas Nef can reduce expression of CD4, Tat reduces the expression of CD28. We hypothesize that the lack of expression of key accessory molecules on CD4 lineage T cells infected with immunodeficiency viruses may make infected T cells more susceptible to recall-antigen-induced programmed cell death.
Firpo
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PP
Regional Primate Research Center, University of Washington, Seattle 98195.
Axberg
I
I
Scheibel
M
M
Clark
E A
EA
D000818:Animals; D000942:Antigens, Bacterial / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000382:microbiology / Q000473:pathology / Q000502:physiology*; D016207:Cytokines / Q000502:physiology; D004261:DNA Replication / Q000502:physiology; D008213:Lymphocyte Activation / Q000502:physiology*; D008251:Macaca; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology*; D015302:Simian Immunodeficiency Virus / Q000302:isolation & purification / Q000502:physiology; D014779:Virus Replication / Q000502:physiology
D000942:Antigens, Bacterial; D016207:Cytokines