Quantification of HIV-1-specific T-cell responses at the mucosal cervicovaginal surface.

Objective: To characterize HIV-1 specific cellular immune responses at mucosal surfaces using a rapid, sensitive enzyme-linked immuno-spot (ELISPOT) technique. Design: Cervicovaginal mononuclear cells obtained from cytobrush and cervicovaginal lavage were assessed for production of interferon-gamma (IFN-y) in response to stimulation by HIV-1 antigens. HIV-1 specific responses were compared in a cross-sectional study of two HIV-1-positive patient groups: women not currently on antiretroviral therapy with peripheral CD4 cell counts > 250 × 10 6 /l (n = 12); and women on highly active antiretroviral therapy (HAART) (n = 9). Methods: Mononuclear cells from peripheral blood or cervicovaginal specimens were assessed in an ELISPOT assay for responses to HIV-1 antigens expressed by recombinant vaccinia viruses. This assay detects primarily CD8 T cells and shows good correlation with MHC class I tetramer staining of cytotoxic T lymphocytes. Results: HIV-1 specific IFN-y spot-forming cells were detected in cervicovaginal samples of one out of nine women (11%) on HAART and five out of 12 women (42%) not currently on HAART. In peripheral blood mononuclear cells, HIV-1 specific IFN-y spot-forming cells were significantly more numerous in women not currently on HAART than in women on HAART (P= 0.009). In most cases, antigens recognized by mucosal T cells were also recognized by PBMC; however, there were exceptions. Conclusions: HIV-1-specific antigen-reactive T cells may be detected in routine, non-invasive gynecological specimens. The results suggest that cervicovaginal HIV-1-specific T cells may be less numerous in individuals on HAART than in those not on HAART, as shown previously for HIV-1-specific cytotoxic T lymphocytes in the peripheral blood.