LEISHMANIA-DONOVANI - TITRATION OF ANTIBODIES TO THE FUCOSE-MANNOSE LIGAND AS AN AID IN DIAGNOSIS AND PROGNOSIS OF VISCERAL LEISHMANIASIS

The fucose-mannose ligand (FML) is a complex glycoprotein fraction pre sent on promastigotes and amastigotes of Leishmania donovani. It parti cipates in parasite interaction with host macrophages in a species-spe cific pattern. We have tested its use in immunodiagnosis of visceral l eishmaniasis (VL) in a recent outbreak in Rio Grande do Norte, north-e ast Brazil. Enzyme-linked immunosorbent assay (ELISA) of low concentra tions of FML in 462 sera showed 100% sensitivity and 96% specificity. The FML-ELISA identified patients with overt VL (P < 0.001 compared to normal sera). It could also identify inhabitants of the endemic area who had incipient or subclinical infection with potentially severe cli nical disease: more than 20% of apparently healthy subjects with a pos itive ELISA for FML developed overt VL during the following 10 months. FML-ELISA reactivity decreased in all patients during treatment, and became negative after parasitological cure. No cross-reaction was obse rved in patients infected with other Leishmania species, nor in those with Chagas disease. Determination of antibody response to FML may be useful in diagnosis of VL and in identifying patients without overt di sease but with a high risk of developing severe VL.