Comparison of the response to PHA and suppressor macrophage function in different age groups of cancer patients and healthy controls.

The mitogenic response of peripheral blood lymphocytes was examined in 37 healthy individuals and in 44 patients with various malignant neoplasms. Tested individuals were divided into three major age groups (20-40; 40-60; and over 60 years of age). There was a significant decrease in Phytohemagglutinin (PHA) response with age in the normal controls, but no significant change with age was observed in the cancer patients. Comparison between the various age groups of cancer patients and their corresponding normal controls did not reveal a significant difference in mitogenic response of the young and middle age groups. However, the older cancer patients responded significantly better compared with their corresponding older normal controls. The reduced responsiveness of older normal controls was partially explained by a high activity of suppressor macrophages observed in this group. Reduction of the proportion of phagocytic cells improved their response to PHA. On the other hand, the activity of suppressor macrophages in the older cancer patients was much less prominent. These observations emphasize the importance of appropriate age grouping when immune function tests in cancer patients are compared with those performed in normal individuals and suggest the possibility of higher mitogen responsiveness in certain age groups of cancer patients.