Detection of HIV-specific cell-mediated cytotoxicity in the peripheral blood from infected children

Abstract

Cytotoxic T lymphocytes may play a significant role in containing the spread of HIV in infected individuals. Although HIV-infection is associated with immune suppression, a vigorous T lymphocyte response has been detected in infected adults. HIV can be transmitted from mother to child, either during pregnancy, when differentiation of the T lymphoid compartment is ongoing, or at birth when the neonate immune system is partially competent. The shorter asymptomatic period of pediatric infection could be related to differences in the host immune control of viral replication. HIV-specific cell-mediated cytotoxicity (CMC) from fresh and in vitro stimulated PBMC of HIV-infected children was measured. CD8+CD3+ T lymphocytes were found to be the major effector population. The vast majority of children examined had detectable HIV-specific CMC. A cross-sectional analysis of CMC responses as a function of clinical status revealed that 71% of asymptomatic children (CDC stage P1) recognized the Env protein, 14% the Gag protein, but none of them recognized the Pol protein. Cytolytic activities directed against these three proteins were detected in two thirds of paucisymptomatic children (P2A). In contrast, symptomatic children (P2B-F) did not show cytolytic activities toward the Gag and Pol proteins, and only 20% recognized the Env protein. In contrast in vitro generated secondary CTL were consistently detected at all stages of disease, even in children with low CD4+ cells counts.