Demonstration of Concanavalin A Receptors on Leptomonas pessoai Cell Membrane*§

Leptomonas pessoai promastigotes cultivated in a synthetic medium were agglutinated with concanavalin A (ConA). Agglutination was predominantly of the flagellar-flagellar type, and was inhibited with sucrose or alpha-methyl-D-mannoside. Cell surface polysaccharides and/or glycoproteins were demonstrated by several cytochemical methods at the fine-structural level. A Con A-horseradish peroxidase-diaminobenzidine (DAB) technic was used to detect Con A receptors in the pellicular membrane of the flagellar pocket region and in the flagellar membrane proper. Somewhat less of the Con A-DAB reaction product was observed in the pellicular membrane enclosing the rest of the cell.