REMARKABLE ACTIVATION OF POLYAMINE BIOSYNTHESIS IN HEMATOPOIESIS AND HYPERPLASIA OF SPLEEN IN MICE WITH HEMOLYTIC-ANEMIA CAUSED BY INFECTION WITH PLASMODIUM-BERGHEI

Ornithine decarboxylase (ODC) activity was markedly induced in the spl een of mice infected with Plasmodium berghei, showing maximal activity at 8 days after the infection. The increase of spleen weight, on the other hand, reached its peak after 14 days of infection. In the blood of P. berghei-infected mice, no increase of ODC activity was observed. This indicated that ODC was induced in the spleen cells, but not in t he parasites themselves which existed in the blood. Polyamines (putres cine, spermadine and spermine) were also elevated in the spleen follow ing induction of the ODC activity. On the other hand, increases of ODC activity and spleen weight were observed in the spleen of mice with h emolytic anemia induced by acetylphenylhydrazine, but the extent of th ese increases were smaller than those in the spleen of mice infected w ith P. berghei. The present results suggest that increases in ODC acti vity and polyamine levels in the spleen of P. berghei-infected mice ar e related to hyperplasia of the spleen (splenomegaly) where the format ion of leukocytes and erythrocytes (hematopoiesis) was dramatically st imulated by the infection.