Lymphocytes forming rosettes with sheep erythrocytes in metastatic pleural effusions.

Percentages of lymphocytes forming rosettes with sheep erythrocytes at 29 degrees C were determined in 10 cancer patients with metastases to the pleural cavity. Compared with normal controls, the patients showed a decreased proportion of rosette-forming cells (RFC) in the peripheral blood. The same patients had elevated levels of RFC in their metastatic pleural effusions. However, 2 patients with benign diseases had normal levels of RFC in their peripheral blood and pleural transudates. These observations suggested that in cancer patients some T-cells might migrate from the peripheral blood and accumulate in sites of tumor infiltration such as the pleural cavity.