Studies on the immunology and serology of Leishmaniasis V. The use of particles as vehicles in passive agglutination tests

Naked sheep erythrocytes, tanned sheep erythrocytes, tanned human erythrocytes of Group O, tanned and formolized sheep erythrocytes and latex particles were sensitized with antigens derived from 8 strains of Leishmania spp. and used in agglutination tests with various antisera and immune sera. Sensitized erythrocytes were formolized and also used in agglutination tests. Successful agglutination tests could be performed consistently with any of these particles provided formalin treatment was omitted. Prior treatment with formalin rendered erythrocytes difficult to sensitize. Formalin treatment of sensitized erythrocytes caused auto-agglutination. The tests with various sera and various absorbed sera revealed serological differences between the strains used. A strain of Leishmania from Panama was shown to be quite distinct from L. mexicana of British Honduras and L. braziliensis of Brazil, and also to be distinct from 2 strains of Leishmania from Costa Rica. The two Costa Rican strains also represented distinct serotypes. Serological differences were detected between L. donovani from India and L. donovani from Kenya. With these tests no serological difference was detected between L. donovani (post-kala-azar dermal leishmanoid) from India and L. tropica from Israel, or between L. braziliensis of Brazil and one strain of so-called L. pifanoi from Brazil.