The enhanced folic and folinic acid contents of erythrocytes infected with malaria parasites

Abstract

Folic and folinic acids were determined, by microbiological assay, in the washed erythrocytes of normal 2-month-old ducks and of similar ducks infected with Plasmodium lophurae, as well as in suspensions of the parasites free from their host cells. Whereas normal red cells contained about 1 mμg per ml of each of the growth factors, the infected red cells contained 20 to 60 mμg per ml of folic acid and 10 to 20 mμg per ml of folinic acid (expressed as leucovorin). It was calculated that an infected erythrocyte contained about 12 × 10 −9 mμg folic acid and 2 to 4 × 10 −9 mμg leucovorin, of which only 2 to 4 × 10 −9 mμg of folic acid and 0.5 to 1.5 × 10 −9 mμg of leucovorin were contained in the malarial parasite itself. Presumably the remainder of the increased folic and folinic acids was in the infected erythrocyte, so that it seems likely that the metabolism of the host cell with respect to these two growth factors was altered by the presence of the parasite.