Serum ceruloplasmin concentrations in rats with primary and transplanted sarcomas induced by nickel subsulfide

Ceruloplasmin (CPN) concentrations were measured by p-phenylenediamine oxidase assay in serums from (a) 30 control Fischer rats; (b) 5 rats with primary sarcomas induced by i.m. injection of nickel subsulfide (alpha Ni3S2), and (c) 12 rats at intervals up to six weeks after s.c. transplantation of four alpha Ni3S2-induced sarcomas. Serum CPN concentrations were not significantly increased in rats with primary sarcomas (mean = 0.38 g per liter) (S.D. +/- 0.05), versus 0.35 g per liter (S.D. +/- 0.04) in controls. In contrast, serum CPN concentrations were increased within 11 to 21 days in all rats with transplanted sarcomas. Maximum concentrations of serum CPN occurred at 31 to 34 days after tumor transplantation, (mean = 0.56 +/- 0.05 g per liter), equivalent to 1.6 +/- 0.2 times the initial CPN concentrations in serums obtained prior to treatment (P less than 0.001). The development of hyperceruloplasminemia in rats with transplanted sarcomas and not in rats with primary sarcomas is attributed to greatly enhanced growth-rates of the transplanted neoplasms.