HIV-specific T-helper activity in seronegative health care workers exposed to contaminated blood

To evaluate human immunodeficiency virus (HIV) type 1-specific cellular immune responses in HIV-seronegative health care workers with occupational high-risk exposures to HIV-infected (HIV-positive) patients.

Peripheral blood mononuclear cells (PBMCs) were obtained after occupational exposures to HIV, and PBMCs from health care workers exposed to HIV-negative patients served as controls. The PBMCs were stimulated in vitro with HIV envelope synthetic peptides. Interleukin 2 (IL-2) production was measured in a bioassay. The HIV antibody status was determined by standard enzyme-linked immunosorbent assays. Exposed individuals were also evaluated for HIV proviral DNA by polymerase chain reaction techniques.

The PBMCs from eight health care workers with high-risk exposures and nine control health care workers were studied.

The PBMCs from all individuals showed strong IL-2 production to control antigens, indicating intact T-helper function. Interleukin 2 production to HIV peptides was detected in PBMCs from six of eight HIV-exposed individuals, but in only one of the nine health care workers exposed to HIV-negative body fluids (P < .008). None of the HIV-exposed health care workers became infected as determined by negative HIV antibody and polymerase chain reaction analysis after follow-up evaluation that ranged from 8 to 64 weeks.

Human immunodeficiency virus-specific T-helper activity was detected in six (75%) of eight HIV-negative health care workers with exposure to HIV-positive body fluids. Potent HIV-specific T-helper activity was detectable 4 to 8 weeks after the exposure and was lost in individuals followed up for 8 to 64 weeks. Three health care workers remained responsive at 8, 19, and 24 weeks. Exposure to HIV without evidence of subsequent infection appears to result in activation of cellular immunity without activation of antibody production.