Rescue of rats from large dose cyclophosphamide toxicity using protein A.

Cyclophosphamide (Cy) is widely used as an effective cytotoxic drug, but its use is limited because of its toxicity. In this report, we describe for the first time the ability of purified protein A (P) of Staphylococcus aureus to reduce Cy-induced toxicity in rats. Protein A-treated animals recover quickly from the toxic effects of Cy. The antitumor property of Cy is not reduced in the P + Cy group. In fact, the latter showed a persistent decrease in tumor volume compared with the Cy group. Protein A may prove to be an effective agent in increasing the therapeutic index of Cy.