The occurrence of Kaposi's sarcoma in young homosexual men is a recently reported condition. The same individuals are at risk for the development of Pneumocystis carinii pneumonia and other unusual infections. These associations suggest these persons are somehow immunocompromised. Evidence of current or prior cytomegalovirus (CMV) infection is seen in a high percentage of these and other homosexual men. CMV infections are known to induce alterations in the immunoregulatory suppressor and helper T lymphocyte populations. The CMV infection is suspect as the cause of immunosuppression in these individuals. We present a case of Kaposi's sarcoma in a homosexual man with CMV cultured from his urine and semen. He showed a marked increase in his suppressor/cytotoxic cell (OKT8-positive) population, as well as a marked decrease in his helper cell (OKT4-positive) population. Mitogen and antigen studies demonstrated absent or markedly diminished responses both in vitro and in vivo. Pokeweed mitogen (PWM)-induced IgG synthesis appeared normal. This patient, as well as the majority of other reported patients with this disease, manifested the HLA-Dr5 phenotype. The immunosuppression in this patient and possibly other similar men appears to be mediated by abnormalities in the immunoregulatory T lymphocytes.
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