Standardization of the dye test for toxoplasmosis.

With the ever-increasing interest being taken in toxoplasmosis more and more requests are reaching laboratories for help in its diagnosis. Prominent among the diagnostic tests employed is the cytoplasm-modifying-antibody (dye) test introduced by Sabin and Feldman (1948). Briefly, this consists in mixing varying dilutions of the patient's serum with peritoneal exudate rich in Toxoplasma from an inoculated mouse, incubating the mixture, and then adding methylene blue. If the patient's serum contains antibody the Toxoplasma will not take up the dye. We have been using this test since 1949. It has been our aim to control or correct variable factors as far as possible so that the results obtained from day to day may be consistent within our own laboratory. Our immediate hope in writing this paper is that we may help others to overcome difficulties that we have encountered, and our ultimate hope that from studies such as ours there may evolve a universally accepted technique that will produce consistent results between laboratories. With these objects in view, we propose to discuss the reagents used in the test and to describe modifications we have thought desirable.