Humoral and Cellular Immune Responses to Synthetic Peptides of the Leishmania donovani Kinetoplastid Membrane Protein-11

Native kinetoplastid membrane protein-11 (KMP-11), purified from crude extracts of Leishmania donovani parasites, activates T cells from individuals who have recovered from visceral leishmaniasis. In this work we used three 38-mer peptides spanning the amino acid sequence of the L. donovani KMP-11 as solid-phase ligands in enzyme-linked immunosorbent assays (ELISAs) and as stimulating antigens in lymphoproliferative assays in order to evaluate humoral and cellular immune responses to well-defined sequences of the protein. Antibody reactivity against the three peptides was measured in plasma from 63 Sudanese visceral leishmaniasis patients (VL) and the percentage of patients with anti-KMP-11 antibodies in ELISA were 37% (KMP-11-1), 30% (KMP-11-2) and 58% (KMP-11-3). The fraction of VL patients with measurable antibody reactivity in one or more of the three ELISAs was 79%. Cross-reactivity to the KMP-11 peptides was detected in plasma from Sudanese patients suffering from Leishmania major infections and in plasma from Sudanese and Danish patients infected with Plasmodium falciparum . In lymphoproliferative assays, 10 of 17 PBMC isolates from donors previously infected with L. donovani showed a response to one or more of the three KMP-11 peptides.