title: Monocytosis-inducing activity (MIA) of serum in Corynebacterium parvum treated mice.
abstract: Intravenous injection of 548 microgram of C. parvum (Lot 0407, Mérieux Laboratories, France) into C57Bl mice produced rapidly appearing monocytopenia which was followed by marked and prolonged monocytosis after the third day. The serum of these animals, collected during the monocytopenic but not the monocytosis phase, showed monocytosis inducing activity (MIA) as was demonstrated by the intravenous injection of the serum into normal test mice. Serum from normal untreated mice or from mice given an intravenous injection of sterile pyrogen-free saline did not cause monocytosis in the test mice. Monocytosis induced in the test animals presented two interesting peaks. The first was observed 2 h after the injection of serum and the second 5 days later. The former was accompanied by a decrease and the latter by an increase in the number of bone marrow monocytes, suggesting that MIA probably represents a releasing activity. The late increase in marrow monocytes is considered as a phenomenon secondary to the initial reduction.
mesh_terms: D000818:Animals; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes; D011425:Propionibacterium acnes