Cytostasis of tumor cell lines by granulocytes from cancer patients and normal human donors

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Abstract
Granulocytes of normal human donors were previously shown to have cytostatic activity in vitro against a variety of tumor cell lines. In the present study, we have compared the levels of granulocyte‐mediated cytostatic activity in cancer patients and normal donors. In an initial study of 25 tumor‐bearing patients and 21 individuals with benign or no disease, decreased cytostatic activity was observed in 84% of the cancer patients. Nine cancer patients with no evidence of disease had reactivity in the normal range. Granulocytes separated by a one‐step method on a double Ficoll‐Percoll gradient showed decreased reactivity. This procedure eliminated the differences previously detected between tumorbearing patients and controls. Addition of either pooled normal AB human serum or autologous serum to the assay restored the reactivity. Only with autologous serum and not with allogeneic serum, were the differences between tumor‐bearing patients and controls again seen. Therefore, in a subsequent study, we examined the effect of serum on cytostasis by normal granulocytes that were isolated on double gradients. We observed lowered serum restorative activity (SRA) in 41 of the 46 (89%) tumor‐bearing patients tested. Fractionation of sera by Sephadex G‐200 chromatography indicated that SRA of both cancer patients and normal donors was in the 100,000 molecular weight region.