[Stimulating action of Brucella melitensis lipopolysaccharide on hemopoiesis in mice]

The bacterial mass, brucellar protective antigen and lipopolysaccharide (LPS) obtained from B. melitensis stimulated the formation of endogenous colonies in the spleen of mice belonging to different strains, subjected to irradiation in sublethal doses. The maximum stimulating effect was observed when the antigens were introduced 24 hours prior to irradiation. LPS introduced in the optimal dose induced an increase in the number of hemopoietic stem cells (HSC) in the s-phase of the cell cycle, thus stimulating the postirradiation survival of mice irradiated in a lethal dose. 24 hours after the injection of LPS the total number of HSC in the spleen increased 1.5 times. These data indicate that LPS has a stimulating effect on hemopoiesis in mice. The effect rendered by LPS is seemingly linked with an increase in the proliferation of HSC and, to a lesser extent, depends on changes in the migration of HSC.