The humoral immune response to the kinetoplastid membrane protein-11 in patients with American Leishmaniasis and Chagas disease: prevalence of IgG subclasses and mapping of epitopes

The kinetoplastid membrane protein-11 (KMP-11) is a major target of the hum oral immune response during Leishmania-infections. The majority of sera fro m visceral leishmaniasis, mucocutaneous leishmaniasis and even some cutaneo us leishmaniasis patients contain detectable IgG antibodies against KMP-11. We also provide evidence that this protein may act as a potent antigen in T. cruzi infections, since most Chagas sera show immunological cross-reacti vity. Therefore, KMP-11 cannot be used as a specific diagnostical tool for the serodiagnosis of leishmaniasis in those regions where both, Leishmania and T. cruzi infections overlap geographically. When analyzing the subclass specificity of the antibody response to KMP-11 we observed the following o rder of reactivity: IgG1 > > IgG3 > IgG2 > IgG4, which is similiar to that seen in crude parasite extract. The mapping of antigenic determinants by us ing synthetic 20-mer peptides revealed the existence of predominantly confo rmational epitopes in leishmaniasis, while 50% of sera from Chagas patients reacted with a particular KMP-11 peptide. These results therefore suggest the presence of disease-specific B-cell epitopes. (C) 1999 Elsevier Science B.V. All rights reserved.