Erythropoietin and cyclophosphamide combination treatment additively enhances immunoglobulin production in mice

Background: Erythropoietin (EPO) is an important component in the treatment of cancer-related anemia, and it is usually combined with chemotherapy. Cyclophosphamide (CP) is a known cytotoxic alkylating agent used in cancer chemotherapy. The antineoplastic activity of CP at low doses is attributed to enhancement of cellular and humoral immunity. We have previously shown that EPO displays anti-neoplastic activity and that EPO treatment is associated with enhancement of both the humoral and cellular immune responses. Objectives: To explore the humoral immunomodulatory effects of combining EPO and low dose CP, thus simulating clinical conditions. Methods: We compared anti-dinitrophenyl (DNP) immunoglobulin (Ig) serum levels in DNP- keyhole limpet hemocyanin (KLH) injected C57BL mice that were treated with either EPO or CP, separately, or with EPO + CP combination. Diluent injection served as a control for CP and EPO treatment. The levels of IgG1, IgG2a and total Ig were measured using enzyme-linked immunosorbent assay in sera samples taken before, and 2 weeks after antigen injection. Results: CP treatment alone resulted in increased anti-DNP IgG1 serum levels, 2 weeks following antigen administration. In contrast, EPO treatment alone significantly enhanced anti-DNP IgG2a levels. The combined treatment of EPO and CP increased both IgG1 and IgG2a, maintaining the effects of each treatment alone. While neither CP nor EPO alone significantly increased anti-DNP total Ig levels, the combined treatment additively led to their elevation. Conclusions: Our findings emphasize a potential role for EPO as an immunomodulator, particularly when administered as a part of a combined treatment with CP.