Leishmania major: glycolipid antigens recognized by immune human sera

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, R_f 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.