Evidence for the existence of a surface receptor for ferriclactoferrin and ferrictransferrin associated with the plasma membrane of the protozoan parasite Leishmania donovani.

Previous work has demonstrated the ability of the promastigote form of the protozoan parasite Leishmania chagasi to utilize iron chelated to lactoferrin and transferrin for growth and metabolism. We have obtained evidence suggesting that the promastigote form of the parasite possesses specific binding sites for lactoferrin and transferrin. Lactoferrin binding appears to be: 1) independent of whether or not the protein contains iron; 2) not inhibited by transferrin; and 3) independent of whether the organism is in log or stationary phase of growth. Transferrin binding is: 1) markedly greater if the protein is iron loaded; 2) inhibited by the presence of lactoferrin; and 3) independent of whether the organism is in log or stationary growth phase. Preliminary ligand blot analyses are consistent with the presence of a protein or proteins which bind lactoferrin and/or transferrin. The relationship to these binding sites to those described in other protozoan species requires further investigation.