Expression of CD28 on CD8+ and CD4+ Lymphocytes During HIV Infection

Abstract

CD28 interaction with B7 molecules, expressed on the membranes of antigen‐presenting cells, costimulates cytokine production, T‐cell proliferation and generation of cytotoxic lymphocytes. The expression of CD28 markers on CD4⁺ and CD8⁺ lymphocytes was studied in a group of subjects at various stages of HIV infection. A reduction in the percentage of CD28‐bearing CD4⁺ and CD8⁺ 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⁺CD28⁻ 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.