The cellular immune response has been reported to be impaired in patients with renal cancer and to be increased by removal of the tumor bulk. T lymphocyte levels in the vein of the neoplastic kidney were investigated in 4 patients to assess the presence of a T lymphocyte inhibiting factor produced by the tumor. T lymphocyte levels resulted in significantly decreased tumorous venous blood, whether compared to arterial, contralateral or peripheral blood. A similar result was not found in 10 control patients. Some hypotheses on the nature of this T lymphocyte inhibition are discussed.
