EFFECTS OF ADMINISTRATION OF CYCLOPHOSPHAMIDE AND ANTI-THYMOCYTE-GLOBULIN ON SERUM LEVELS OF COMPLEMENTS C1q AND C3 IN MICE

Serum levels of the initiating complement component (C1q) in the classical pathway and those of an essential triggering component (C3) in the alternative pathway were quantified immunochemically in parallel with those of the immunonoglobulin G (IgG) in BALB/c mice, each of which was given a single dose of cyclophosphamide (CY) and/or rabbit anti-mouse-thymocyte-globulin (anti-TG) intraperitoneally. In the CY-treated mice, both C1q and IgG levels were significantly suppressed from 2 through 14 days after the treatment ; such suppression was more conspicuous in male than in female mice. In contrast, C3 levels were markedly increased in these mice of both sexes from 2 through 7 days after the same treatment. In anti-TG-treated mice of both sexes, only C1q levels were significantly suppressed from 2 through 10 days after the treatment ; however, neither their C3 nor IgG levels were much influenced. Both T and B lymphocytes in peripheral blood of these mice were significantly diminished : CY affected more severely B cells ; in contrast, anti-TG had a more severe influence on T cells. These results suggest that there may be some metabolic and/or developmental interrelationships among serum C1q levels, functions of immune lymphocytes, and their producing immunoglobulins and/or lymphokines