CD95 Expression and Apoptosis during Pediatric HIV Infection: Early Upregulation of CD95 Expression

The Nef-Mediated AIDS-Like Disease of CD4C/Human Immunodeficiency Virus Transgenic Mice Is Associated with Increased Fas/FasL Expression on T Cells and T-Cell Death but Is Not Prevented in Fas-, FasL-, Tumor Necrosis Factor Receptor 1-, or Interleukin-1β-Converting Enzyme-Deficient or Bcl2-Expressing Transgenic Mice

“…This finding also parallels some reports showing similar increased expression of Fas or FasL in CD4 ϩ or CD8 ϩ T cells or the peripheral blood mononuclear cells of SIV-infected macaques or HIV-infected patients or in T cells infected in vitro with HIV-1 (10,20,30,32,35,53,71,82,93), although other studies came to opposite conclusions (19,31,60,76). Attempts to assess the Fas pathway in HIV-1-infected cells or in cells from SIV-infected macaques or HIV-infected individuals also led to controversial results, some investigators finding enhanced Fas-mediated apoptosis (14,16,31,35,82,97), while others did not (19,20,34,39,60,68,95).…”

“…Fas and FasL have been shown to be upregulated on the CD4 ϩ and CD8 ϩ T cells or peripheral blood mononuclear cells of HIV-1-infected patients or SIV-infected macaques or in T cells infected in vitro with HIV-1 (10,20,30,32,35,53,71,82,93), and these lymphocytes were shown to have increased susceptibility to Fas-mediated killing (14,16,31,35,82,97). In particular, the induction of FasL or Fas expression and apoptotic cell death of CD4 ϩ and CD8 ϩ T cells by HIV-1 or SIV were found to be dependent on a functional nef gene (30,32,93,94,97).…”

Ontogenic changes in CD95 expression on human leukocytes: prevalence of T-cells expressing activation markers and identification of CD95−CD45RO+ T-cells in the fetus

“…Most knowledge regarding fetal Tcells has come from the analyses of neonatal T-cells obtained from UCB. Studies have shown neonatal Tcells to be comprised of primarily CD45RA þ naive/ resting T-cells [11 -15] that express low levels of the activation marker CD95 [21,24]. In contrast, our examination of midgestation fetal tissues indicates that the frequency of T cells that express CD95 in these tissues is comparable to that of adult T-cells.…”

“…Triggering of programmed cell death by CD95 activation, through interaction with CD178, leads to clearance of activated T-cells and thereby limits immune responses [22,23]. Neonatal T-cells express less CD95 than their adult counterparts [21,24]. Expression of CD95 is also low to negative on SP thymic cells from midgestation thymic tissues, although CD95 is expressed on immature T-cell progenitors [25].…”

“…These data suggest that CD95 expression increases with the maturation of the immune system. In this regard it is worth noting that CD95 expression can increase more rapidly in children infected by the human immunodeficiency virus [24].…”