Abstract

Cytotoxic T lymphocyte (CTL) responses to human immunodeficiency virus type 1 (HIV-1) gag proteins were studied prospectively in 17 children (12 infected) born of mothers with HIV-1 seropositivity and in five pediatric patients with hemophilia infected by transfusion of HIV-1-contaminated factor VIII concentrate. B lymphoblastoid cells infected with vaccinia virus vectors expressing HIV-1 gag gene products were combined with autologous peripheral blood mononuclear cells to detect circulating CTLs. Effector cells were defined by monoclonal antibody-mediated, complement-dependent cytolysis. Circulating HIV-1 gag-specific cytotoxic responses were detectable in 4 of 5 HIV-1-infected pediatric hemophilic patients, and were similar in magnitude to those previously described in adults. In contrast, circulating HIV-1 gag-specific cytolysis was detectible in only 3 of 12 vertically infected children. Depletion data revealed that the majority of detectible gag-specific cytolysis was CD8 T cell-mediated. No apparent relationships between CD4 T cell counts, CD8 T cells counts, or serum p24 antigen levels and CTL responses were seen. Deficient CTL development may, in part, explain the more rapid onset of symptomatic disease following vertical HIV infection.