Leishmania major: glycolipid antigens recognized by immune human sera

Abstract

Extraction of whole promastigotes with a mixture of hexane-isopropanol yielded two carbohydrate-lipid fractions immunologically active against immune sera from patients with cutaneous leishmaniasis (CL): CLF-1 and CLF-2. Thin layer chromatography (TLC) separated both fractions into eight bands labeled A-H. Four of these bands, Rf 0.19, 0.25, 0.39 and 0.48 (A, B, C and E, respectively) were recognized by antibody from patients with CL in a solid phase radioimmunoassay. Antigens were also detected by autoradiography after immunoblotting of TLC. Compound A could be labeled biosynthetically with [3H]oleic acid, [14C]galactose, [14C]mannose, [14C]glucose and [32P]phosphate. B incorporated [14C]galactose, [14C]mannose, [14C]glucose and [14C]myo-inositol. C was labeled with [14C]galactose and [14C]mannose, while E incorporated [14C]glucose, [14C]mannose, [3H]oleic acid and [14C]myoinositol. Two antigens (A and B) could be also labeled on the surface of living promastigotes using galactose oxidase and [3H]sodium borohydride. Experimental data showed that CLF-1 and CLF-2, both carbohydrate-containing fractions, had different chromatographic patterns from excreted factor (EF), a polysaccharide antigen from Leishmania. The present study characterizes glycolipid molecules from L. major promastigotes, able to stimulate the immune system from patients with CL.