Untreated patients with Hodgkin's disease (HD) have a blood T- lymphocytopenia mainly caused by a reduction of the CD4+ subset. Indirect support for a sequestration of T cells in the spleen and tumor- involved lymphoid tissue has accumulated. To test the hypothesis that the blood CD4 T-lymphocytopenia in patients with HD is caused by an altered lymphocyte traffic, 12 untreated HD patients and five in complete clinical remission (CCR) were studied. Blood lymphocytes were collected by leukapheresis and gradient centrifugation, and were further purified by an adherence step. The cells were labeled with indium-111 oxine and reinfused intravenously into the patient. The radioactivity of CD4+ and CD8+ blood lymphocytes separated by immunoabsorption was measured from serial blood samples. CD4+ cells were eliminated more rapidly in untreated patients than patients in CCR. Repeated gamma camera imaging after autotransfusion of indium-111 oxine labeled cells demonstrated an accumulation of radioactivity in tumor-involved tissue of untreated patients. These findings support the concept of an enhanced elimination of CD4+ cells in patients with active HD that may contribute to the observed blood T-lymphocytopenia and may reflect a biologic response to the tumor.