In vivo evaluation of immune responses in leishmaniasis: the use of cross-species leishmanin preparations for skin testing.

Skin test reactivity to two commercial preparations of Leishmania major leishmanin was evaluated in leishmaniasis patents from Ethiopia (L. aethiopica) and Nicaragua (probably L. braziliensis complex). The purpose of using different preparations of L. major was to evaluate whether L. major skin test antigens could generally be used to detect leishmaniasis due to L. aethiopica and L. braziliensis. One preparation was superior in identifying the majority (83-90%) of confirmed cases of local cutaneous leishmaniasis (LCL) from Ethiopia. In vitro responses to promastigotes of Leishmania spp. correlated well with leishmanin positivity to this preparation. The skin test antigen, which performed less well (showing a positive result in only 50% of the LCL patients), showed promise when used to test active and cured cases of leishmaniasis in Nicaragua (positive result in 92% of the active and cured patents). Cross-reacting Leishmania spp. may be considered for use in the preparation of standardized leishmanin antigen; however, differences in the commercial preparation or the diluent in which the parasites are prepared may affect antigenicity and thus its efficacy in detecting different forms of leishmaniasis in different geographic areas.