Lymphocyte transformation to phytohaemagglutinin and delayed hypersensitivity related to age and previous cancer history.

Declining immunosurveillance in old age has been considered one possible explanation for the increased incidence of cancer in the elderly. This study was set up to search for evidence of persistent immunodeficiency in patients with a past history of cancer. Lymphocyte responses to phytohaemagglutinin and cutaneous delayed hypersensivity were assessed in fifty-seven elderly subjects who had successfully completed treatment for cancer more than 18 months previously and compared with those of forty-three healthy controls matched for age and sex. Although a significant difference between mean tritiated thymidine uptake was observed in the lymphocyte response to phytohaemagglutinin (cancer patients 1859 cpm, control 2502 cpm), this could be explained by an unexpectedly prolonged effect of radiotherapy. Mean counts for those twenty-six cancer patients receiving radiotherapy within the period 18 months to 4 years were low (1257 cpm), but were normal (2366 cpm) for the remainder. A significant negative correlation of lymphocyte transformation with age was confirmed in both groups. There was no significant difference in cutaneous delayed hypersensitivity response to commonly encountered antigens. Whilst recognising that these tests do not comprehensively assess immune function, the present results provide no support for the theory that an age-related decline in immune function contributes to the heightened incidence of cancer in the elderly.