The response to phytohaemagglutinin (PHA) of lymphocytes from cancer patients

The uptake of tritiated thymidine by lymphocytes from 100 cancer patients and 31 normal subjects was tested in the presence and absence of phytohaemagglutinin (PHA) in a medium containing autologous or homologous serum. Significant differences were found between normal subjects and cancer patients in both the time course and degree of uptake. Serum from normal individuals restored the response of lymphocytes from cancer patients towards normality whilst serum from other cancer patients had no effect. Serum from cancer patients impaired the response of normal lymphocytes.