We have detected
antibodies, in the sera of
Chagas disease,
Kala-azar and
Mucocutaneous leishmaniasis patients, that bind multiple
antigens shared between the three causative agents. The
Chagas disease sera showed 98 to 100% positive results by ELISA when the Leishmania braziliensis and Leishmania chagasi
antigens were used, respectively. The
Kala-azar sera showed 100% positive results with Trypanosoma cruzi or L. braziliensis
antigens by immunofluorescence assays. The
antibodies in the sera of
Mucocutaneous leishmaniasis patients showed 100% positive results by ELISA assays with T. cruzi or L. chagasi
antigens. Furthermore, the direct agglutination of L. chagasi promastigotes showed that 95% of
Kala-azar and 35% of
Mucocutaneous leishmaniasis sera agglutinated the parasite in dilutions above 1:512. In contrast, 15% of Chagas sera agglutinated the parasite in dilutions 1:16 and below. Western blot analysis showed that the Chagas sera that formed at least 24 bands with the T. cruzi also formed 13 bands with the L. chagasi and 17 bands with the L. braziliensis. The
Kala-azar sera that recognized at least 29 bands with the homologous
antigen also formed 14 bands with the T. cruzi and 10 bands with the L. braziliensis
antigens. Finally, the
Mucocutaneous leishmaniasis sera that formed at least 17 bands with the homologous
antigen also formed 10 bands with the T. cruzi and four bands with the L. chagasi
antigens. These results indicate the presence of common
antigenic determinants in several protozoal
proteins and, therefore, explain the serologic cross-reactions reported here.