Abstract
Enriched fractions of mature and immature neutrophil granulocytes, isolated from guinea pig bone marrow, were assayed for ornithine decarboxylase activity and polyamine content. The results show that immature granulocytes contain at least ten times more ornithine decarboxylase activity and two times more spermidine than mature granulocytes. The incorporation of 14C-ornithine into putrescine and spermidine of intact immature granulocytes was three to four times and ten times, respectively, that of mature granulocyte preparations. Six hours after an inflammatory stimulus, transient increases of 14-fold and 3-fold in the activities of ornithine decarboxylase and S-adenosyl- L-methionine decarboxylase, respectively, were observed in immature bone marrow granulocytes. At this time the incorporation of 14C- ornithine into putrescine and spermidine in bone marrow granulocytes from stimulated animals was 14 times that of cells from controls. A maximum increase in DNA synthesis in these cells during the inflammatory response occurred 6 hr after the maximum increase in the polyamine synthetic activity. Together these data suggest that polyamine synthesis in the granulocyte compartment of the bone marrow is associated chiefly with immature proliferating cells and that increased polyamine synthesis precedes increased granulocyte proliferation in the bone marrow following an inflammatory stimulus.
