The decreased expression of CD3 ζ chains in cancer patients is not reversed BY IL‐2 Administration

The mechanisms underlying the impaired immune response frequently observed in cancer patients are poorly understood. Recently, a decreased expression of the signal‐transducing CD3 ζ chains has been shown to occur in patients with colorectal or renal‐cell carcinoma. Here, we have investigated the expression of the ζ molecule on lymphocytes from patients with advanced cancers including renal‐cell carcinoma (n = 21), hepatic colorectal carcinoma metastases (n = 6), head‐and‐neck squamouscell carcinoma (n = 7) or miscellaneous tumors (n = 7), using flow cytometry analysis of PBMCs with monoclonal antibody specific for the cytoplasmic domain of the ζ chain. The same analysis was also performed with patients undergoing IL‐2 therapy (from 5 days up to 3 months i.v. or s.c). PBMCs from patients (n = 41) showed a significant decrease in expression of the ζ chains as compared to the levels found in lymphocytes from healthy controls (n = 15), which was not reversed by IL‐2 administration. Together, these results suggest that an alteration in the expression of the ζ‐chain‐transducing element in PBMCs may be a common cause of progressive immunosuppression in advanced cancer patients and that IL‐2 is not sufficient to reverse this situation in vivo.