Reversal of defective lymphoproliferation in postoperative patients with colon cancer.

To establish a method for evaluation of immunological parameters in small blood samples, a whole blood technique was developed for the estimation of mitogen- or antigen-induced proliferation. Studies regarding cellular immunity in patients with colon cancer were done with 108 patients in all tumor stages, aged 32 to 80 years. They were studied before surgery and 10 days after operation. A group of 35 patients were further tested 3 months after surgical treatment. In patients with colon cancer the proliferative responses of peripheral blood lymphocytes to mitogens were significantly lower in comparison to healthy controls. These results were found when the response to concanavalin A, phytohemagglutinin, OKT 3, and pokeweed mitogen were analyzed preoperatively and 10 days postoperatively. There was no relation to the stage of disease. The marked reduction of mitogen responses was followed by a gradual return toward normal values 3 months after surgical resection of neoplastic growth in 80% of the patients. Our studies indicate that the defects were largely restored when testing was performed 3 months after operation. Using this result, it will be possible to perform long-term studies in order to establish if there is a correlation between the return to normal immune reactivity and the survival of individual patients.