Studies on Hemoflagellates: III. The Specificity of Serological Reactions of Leishmania Donovani, L. Brasiliensis, L. Tropica, and Trypanosoma Cruzi

Abstract

A serological study was made of culture organisms of L. donovani, L. brasiliensis, L. tropica, and T. cruzi with young guinea pigs as sources of antiserums produced by repeated injn. of massive amts. of thoroughly washed organisms. For agglutination reaction the micro-slide test with living organisms as antigen gave the best results. For precipitation reaction the ring test was the most delicate. For complement-fixation reaction, glycerinated and lyophilized antigens produced equally good results, but the latter was more stable. The lytic effect of antiserums at low dilutions could not be eliminated with the Leishmania organisms, but was eliminated with T.. cruzi, using the more resistant trypanosome and slender crithidial forms harvested from old cultures. From this study, the following essential features have been observed: The culture forms of these 4 spp. of hemoflagellates produced in guinea pigs good agglutination and complement-fixation antibodies and weak precipitation antibodies. In all 3 types of serological reactions, cross-reactions occurred among all antiserums against the heterologous antigen organisms, but were usually considerably weaker and occurred at much lower titres than homologous reactions. Although the degree of cross-reactions of the antiserums against the heterologous antigen organisms was rather irregular, the anti-L. brasiliensis serum seemed to show more cross-reaction than the other 3 antiserums. Absorption of antiserums with their homologous antigen organisms removed the species as well as the cross-reacting antibodies, while absorption of the antiserums with the heterologous antigen organisms removed all the respective antibody and part or all of the other cross-reacting antibodies and reduced the agglutination titre against the homologous antigen organisms. Absorption of the heterologous antiserums with organisms of L. brasiliensis seemed to have removed them more completely than any of the other 3 organisms. It is concluded that the culture forms of L. donovani, L. brasiliensis, L. tropica, and T. cruzi have both species-specific and common antigens, that the species-specific antigen is predominant, and that the common antigen is probably a mosaic of several antigen components which vary qualitatively and quantitatively in different spp. of hemoflagellates.