Flowcytometric analysis ofthestimulatory response ofT cell subsets from normalandHIV-1+ individuals tovarious mitogenic stimuli invitro

SUMMARY A novel technique isdescribed whichallows thestudy oftheresponsesofT cell subpopulations stimulated inbulkcultures without interfering withcell-cell interactions. Thenumberand phenotype oflymphoblasts developing following stimulation withphytohaemagglutinin (PHA), anti-CD3, staphylococcal protein A (SPA)andpokeweed mitogen (PWM)was determined in HIV-1 -andHIV- 1+patients using a new five-parameter flowcytometric method. We foundthat normal Tcells responded faster toPHA thantoany oftheother mitogens tested. Thepeakofthe PHA responseoccurred on day3,followed byanti-CD3 andSPAon day4andPWM mitogen on day5.Although PHA andanti-CD3 stimulated up to95%and80%oflymphocytes, respectively, SPAandPWM stimulated only40%and30%ofcells, respectively. Adefective Tcell responsewas observed inlymphocytes cultured fromasymptomatic HIV-1+patients compared withnegative controls. Thisloss ofresponsewas related toa selective mortality ofTcells following mitogenic stimulation, referred toasactivation-associated lymphocyte death(AALD).Theresults showed that stronger mitogens (PHAandanti-CD3) induced AALD inalarger proportion (50-60%) ofT cells thanweaker mitogens suchasSPAandPWM (30-40%), andthatAALD affected different lymphocyte subsets todifferent extents. AALD occurred more frequently intotal CD8+and CD45RO+Tcells compared withCD4+andCD45RA+Tcells, butmemory CD4+Tcells were thepopulation mostseverely affected insamples fromHIV-1+ donors.