ENV-SPECIFIC CYTOTOXIC T-LYMPHOCYTE RESPONSES IN HIV SERONEGATIVE HEALTH-CARE WORKERS OCCUPATIONALLY EXPOSED TO HIV-CONTAMINATED BODY-FLUIDS

Identification of the components of protective immunity are crucial for the development of effective prophylactic and therapeutic vaccine strategies, Analysis of HIV-specific responses in exposed but uninfected individuals might thus provide a unique resource to elucidate the components and correlates of protective immunity to HIV. In the present study we analyzed HIV-specific cytotoxic and helper T lymphocyte responses in health care workers (HCW) exposed to body fluids from HIV-positive individuals, HCW exposed to blood from HIV-negative individuals as well as healthy donors served as controls, Cytotoxic T lymphocyte (CTL) responses to HIV envelope (env) peptides were detected in 7/20 (35%) HCW exposed to HIV-positive blood and in none of the 20 health care workers exposed to uninfected blood or the seven healthy blood donors studied, HIV-specific CTL responses were detected only after in vitro stimulation, and were MHC class I restricted, No MHC class I restriction elements were uniformly identified among the different responders, 21/28 (75%) HCW exposed to contaminated blood responded to env as measured by IL-2 production to the peptides, in contrast to only 9/38 (24%) HCW exposed to HIV seronegative blood and 3/35 (9%) healthy blood donors. All the HIV exposed individuals were seronegative on repeated ELISA tests, and no evidence of infection was obtained by PCR analysis, These findings indicate that a single exposure to HIV can induce CTL immunity to HIV antigens, in the absence of other evidence of infection.