Comparison of CD8(+) cytotoxic lymphocyte subsets in peripheral blood from participants with human immunodeficiency virus and chronic fatigue immune dysfunction syndrome

The CD8$\sp+$ CTL subsets of peripheral blood from control individuals and study participants with CFIDS and HIV infection were quantified using a flow cytometer and a monoclonal antibody (S6F1) to an epitope of the LFA-1 molecule. HIV (or HTLV III) induces a strong CTL response in infected individuals. An increase in absolute number of CTL (as compared to controls) in HIV infected participants with an absolute CD4$\sp+$ count $>$ 500 cells/mm$\sp3$ was lost as the CD4$\sp+$ count dropped below 500 cells/mm$\sp3$. There was no significant change in CTL number as the disease progressed toward AIDS. CFIDS has recently been associated with a human T lymphotropic virus (HTLV II)-like virus. Participants with CFIDS had no significant difference in the absolute number of circulating CTL compared with control participants. The difference in host immune response may be due to differences in immunogenicity of the etiological agents.