Evaluation of phagocytic activity in neoplastic patients treated with subcutaneous recombinant IL-2

Immunostimulating and immunosuppressive events have been noted during rIL- 2 immunotherapy and cell-mediated immune deficiencies have been reported in the neutrophil and monocyte functions, determining a high incidence of infections in patients during intravenous rIL-2 treatment. The phagocytic activity of monocytes/macrophages and granulocytes was evaluated in 10 advanced solid tumor patients treated with subcutaneous rIL-2. Several indirect parameters of phagocytosis were also considered, such as Neopterin, Beta2 microglobulin, IL-2 soluble receptor, and the C3 and C4 fractions of the complement system. A decreased phagocytosis was demonstrated after subcutaneous rIL-2 administration together with an increase of indirect parameters of granulocyte/macrophage activity. Therefore, cellular activation does not seem to correspond to actual phagocytosis which is probably due to IL-2-induced secondary cytokines or to rIL-2 inhibitory effects.