Expression of CD28 on CD8 super(+) and CD4 super(+) lymphocytes during HIV infection

CD28 interaction with B7 molecules, expressed on the membranes of antigen-presenting cells, co-stimulates cytokine production, T-cell proliferation and generation of cytotoxic lymphocytes. The expression of CD28 markers on CD4 super(+) and CD8 super(+) lymphocytes was studied in a group of subjects at various stages of HIV infection. A reduction in the percentage of CD28-bearing CD4 super(+) and CD8 super(+) cell subsets was observed during the asymptomatic stage of the disease. This reduction was more pronounced in AIDS than in non-AIDS patients. At the same time, an increase in the absolute CD8 super(+) CD28 super(-) cell number (greater in stage A than in stage B and C subjects) was observed in HIV-infected patients. The finding of an altered pattern of CD28 expression on T cells might per se explain certain early defects in the cytokine pattern and in the immune response peculiar to HIV-infected patients.