PURIFICATION, PARTIAL CHARACTERIZATION AND IMMUNOLOCALIZATION OF A PROTEOPHOSPHOGLYCAN SECRETED BY LEISHMANIA-MEXICANA AMASTIGOTES

The intracellular amastigote form of the parasitic protozoon Leishmani a mexicana expresses a high-molecular weight phosphoglycan, which is a ntigenically related to the surface glycolipid lipophosphoglycan and t he secreted enzyme acid phosphatase of Leishmania promastigotes. This antigen was purified from a cell-free homogenate of infected mouse tis sue and from amastigotes. Compositional and immunological analysis of the purified components indicate a proteophosphoglycan structure consi sting of serine-rich polypeptide chains and mild acid-labile phosphool igosaccharides capped by mannooligosaccharides. Immunofluorescence and immunoelectron microscopy of parasitized mouse peritoneal macrophages and infected mouse tissue suggest that the proteophosphoglycan is sec reted in large amounts by amastigotes via their flagellar pockets into the parasitophorous vacuoles of host cells. In some infected marcopha ges proteophosphoglycan is also located in vesicles apparently origina ting from the parasitophorous vacuole, which demonstrates redistributi on of a secreted amastigote antigen in parasitized host cells.