Functional state of CD4+ and CD8+ T lymphocytes and their role in the slow progression of HIV infection in pediatric patients.

Objective: To evaluate simultaneously the functional state of CD4+ and CD8+ T lymphocytes from Venezuelan HIV-1-infected pediatric patients.

Methods: Children were assigned to subgroups of rapid progressors (RPs) and slow progressors (SPs), based on clinical features. To determine the degree of CD4+ and CD8+ T-lymphocyte functionality, flow cytometry techniques were used, and diverse parameters of the functionality of these cells were characterized by ex vivo tests, such as expression of CD95/Fas and CD127, and frequency of apoptosis. In addition, we determined, in cultured peripheral blood mononuclear cells, HIV-specific proliferation and the production of interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma), besides measuring intracellular IFN-gamma in CD4+ T cells.

Results: Our results indicate that several molecular and cellular mechanisms of CD4+ and CD8+ T lymphocytes are deteriorated in RPs in comparison with SPs and controls. Indeed, both types of T lymphocytes from RPs exhibited an increased expression of CD95/Fas (p < 0.01), a significantly reduced expression of CD127 (p < 0.01), and an augmented frequency of apoptosis (p < 0.01). Furthermore, T cells from these patients displayed a diminished capacity of mitogen proliferation (p < 0.05), a reduced percentage of IFN-gamma producing CD4+ T lymphocytes (p < 0.05), and a smaller capacity of IL-10, TNF-alpha and IFN-gamma production (p < 0.01) in comparison with SP and control patients.

Conclusion: Our findings indicate that the decline of the normal T lymphocyte molecular and cellular responses is related to a rapid progression and a decreased resistance to HIV-1 infection in children.