Expression of costimulatory molecule CD28 on T cells in human immunodeficiency virus type 1 infection: functional and clinical correlations.

To study the functional integrity of T cells from human immunodeficiency virus type 1 (HIV-1)-infected persons, CD4+ and CD8+ cells were examined for proliferation and secretion of interleukin-2 (IL-2) in response to staphylococcal superantigens and antibodies to CD3 and the alpha beta T cell receptor. A functional defect within CD8+ but not within CD4+ cells from HIV-1-infected persons was observed. Within CD8+ cells, proliferation and secretion of IL-2 was restricted to cells expressing the costimulatory molecule CD28. Such cells were proportionally reduced in HIV-1-infected persons. In patients with advanced immunodeficiency, however, evidence of functional derangement was found also within the CD28+ CD8+ cells. In a cross-sectional study of 73 HIV-infected persons and 15 controls, a significant correlation was observed between the number of CD28+ CD8+ cells and the presence of HIV-related disease. Our results suggest that regulation of expression of CD28 may play an important role in the immunopathogenesis of AIDS.