Cisplatin-induced nonimmunologic adsorption of immunoglobulin by red cells

Antibodies to cisplatin, an extensively used anticancer chemotherapeutic agent, have been implicated previously as a cause of immune hemolytic anemia. Investigation of a suspected case of cisplatin-induced hemolytic anemia in a 40-year-old man demonstrated that IgG could be adsorbed nonimmunologically by reagent red cells in vitro. This phenomenon was found to be a source of possible error in the interpretation of studies identifying specific cisplatin antibodies. Furthermore, cisplatin was found to be capable of producing a positive direct antiglobulin test (DAT), owing to the nonspecific adsorption of immunoglobulin and complement in vivo. Although this finding did not result in acute hemolysis, it may cause confusion in the investigation of DAT-positive hemolytic anemias. We question whether previous reports of cisplatin-induced hemolytic anemia are accurate in their assessment that such hemolysis was mediated immunologically. Future studies of suspected cases of hemolysis induced by this drug should include serologic investigation adequate to demonstrate the presence of specific cisplatin antibodies. A positive DAT in such patients should not be considered proof of drug-induced immune hemolytic anemia.