Modulation of macrophage response to interleukin-2 immunotherapy by interleukin-3 in cancer patients.

: It has been observed that neopterin, a specific marker of macrophage activation, increases during cancer immunotherapy with IL-2, and this effect is mediated by interferons produced by IL-2-stimulated lymphocytes. Moreover, our previous studies have shown that neopterin rise during IL-2 immunotherapy is associated with an enhanced release of soluble IL-2 receptor (SIL-2R), which may suppress IL-2-dependent immune functions. This finding would suggest that neopterin increase may be related to the generation of suppressive events, which occur during IL-2 immunotherapy. On the basis of the documented modulatory effect of IL-3 on macrophage functions, we have evaluated the influence of IL-3 on neopterin secretion during IL-2 immunotherapy. The study was performed in advanced lung cancer patients. We have investigated 9 immunotherapeutic courses consisting of IL-2 (6M IU/day s.c. for 5 days/week for 3 weeks) plus IL-3 (1 microgram/(kg x day) i.v. for 14 days, starting 7 days before IL-2). The results were compared to those found during 18 courses with IL-2 alone. Mean neopterin levels increased significantly during IL-2 alone, but not in response to IL-3 plus IL-2. SIL-2R rise was significantly higher during IL-2 than during IL-3 plus IL-2. Mean numbers of NK cells and activated lymphocytes increased significantly in both groups of patients, but were significantly lower at the end of the treatment in patients receiving IL-2 alone than in those treated with IL-3 plus IL-2.(ABSTRACT TRUNCATED AT 250 WORDS)