The influence of 5-fluorouracil on cellular and humoral immunity in cancer patients.

The effects of 5-fluorouracil (5-FU) on the immune functions of twelve patients with disseminated cancer were studied, using as parameters the peripheral blood lymphocyte count, serum immunoglobulin levels, titers of natural blood group antibodies, percentages of E and EAC rosette forming cells, and lymphocyte proliferative responses to PHA and PPD. No effects on the humoral immune functions or on the percentages of E and EAC rosette forming cells were observed. 5-FU caused a decrease in the proliferative responses of lymphocytes to PHA and PPD. The patients could be divided into two groups: those surviving for six months or more, and those succumbing earlier. The latter ones had already initially poor proliferative responses, particularly to PPD, and the response strongly decreased during the 5-FU treatment. In the patients with a longer survival time, the effects of 5-FU on the PPD and PHA responses were not as striking.