HIVinfectionisassociatedwithimmunosuppressioncausedbyadramaticreductioninthehelperTcellpopulation.ThelossofhelperTcellsmaybecausedbyHIV-inducedapoptosisofbothinfectedanduninfectedhelperTcells.HIVusestheCCR5chemokinereceptorasacoreceptorformacrophagecellentryandupregulatesfas-ligandonthesecells.CD4onhelperTcellsisessentialforviralcellentryandinfection.Cross-linkingofCD4ontheTcellsurfacemaybeinvolvedinupregulationofFasandsensitizationofTcellstoapoptosisinducedbytheFas/Fas-ligandinteraction. Contributor:GlennCroston,PhD. REFERENCES:Badley,A.D.etal.(1996)UpregulationofFasligandexpressionbyhumanimmunodeficiencyvirusinhumanmacrophagesmediatesapoptosisofuninfectedTlymphocytes.J.Virol.70(1):199-206Desbarats,J.,Freed,J.H.,Campbell,P.A.,Newell,M.K.(1996)Fas(CD95)expressionanddeath-mediatingfunctionareinducedbyCD4cross-linkingonCD4+Tcells.Proc.Natl.Acad.Sci.U.S.A.93(20):11014-8Dockrell,D.H.etal.(1998)TheexpressionofFasLigandbymacrophagesanditsupregulationbyhumanimmunodeficiencyvirusinfection.J.Clin.Invest.101(11):2394-405
