Perhaps more important has been the examination of the CD8 cells in these ESN individuals. Because IFN-γ production correlates with cytotoxic functions, the CD8 T lymphocyte IFN-γ response to HIV p24 peptide in ESN women was compared with HIV-positive individuals. Approximately 40% of ESN women had a CD8 IFN-γpositive response, and this was five times lower in magnitude than that of HIV-positive women. The breadth of the response was very narrow and focused primarily on one peptide that is similar to KK10 protective peptide when compared with the HIV-positive group. In HIV-positive women, lower CD4 counts influenced the number of CD8 cells producing IFN-γ, which may undermine the ability to control HIV. These results indicate ESP women have an HIV-1 p24 peptide-specific CD8 IFN-γ response, providing evidence to the specificity needed for an effective HIV vaccine.