Antigen/Antibody Analyses in Leishmaniasis.

Four major objectives were accomplished during the first year of these investigations. A simple modification of existing methods for growing culture forms of Leishmania spp. in larger numbers was determined. This modification was the addition of fetal bovine serum which had been selected for optimal ability to support the growth of mouse lymphocytes in cultures. Immunoblotting procedures were developed for the identification of reactions of antibodies in human sera with antigens of protozoan parasites. It was found that enzyme substrate reactions had distinct advantages over typical autoradiographic procedures. Analyses of various sera identified a number of antigens of protozoan parasites which may be useful in discriminating infections caused by various species of Leishmania and between these parasites and Trypanosoma cruzi. These results, however, are complicated by the surprising observations that normal, uninfected persons contain antibodies in their sera which frequently show strong reactions to numerous antigens of Leishmania spp. and T. cruzi. These natural antibodies are the sources of confusing false-positive reactions in immunodiagnostic procedures. Whereas it has been known for some time that natural antibodies exist in the serum of many uninfected individuals, the apparent diversity of the specificity of these antibodies, as determined in the present study, was not known. Future studies will examine the nature of these natural antibodies and attempts will be made to identify antibodies induced specifically as a result of active infections.