Characterization of T cell subsets involved in the production of IFN-gamma in asymptomatic HIV-infected patients

Cells capable of interferon (IFN)-gamma synthesis following mitogenic stimulation can be detected and quantified by a recently developed immunofluorescence assay and flow cytometric analysis, The production of IFN-gamma was investigated in a cohort of 20 asymptomatic human immunodeficiency virus (HIV)-seropositive patients with normal numbers of CD4(+) lymphocytes, and in 10 healthy subjects, About 60% of asymptomatic stage A1 patients had increased percentages of blood lymphocytes capable of IFN-gamma synthesis, as compared to healthy subjects, The difference reflected the relatively higher numbers of CD8(+) cells, in particular the CD8(+) T cell subset lacking CD28 antigen expression, The strong correlation between the CD4(+)/CD8(+) ratio and the CD8(+)CD28(+)/CD8(+)CD28(-) ratio suggests either a role for CD4(+) cells in controlling the CD28(+) phenotype or a role for CD8(+)CD28(-) cells in the decline of CD4(+) lymphocytes, The peculiar ability of CD8(+)CD28(-) cells to produce high amounts of IFN-gamma, as compared to CD8(+)CD28(+) cells, supports the hypothesis that the CD8(+)CD28(-) lymphocytes constitute a population that is functionally distinct from their double-positive counterparts.