Serum colony stimulating activity and colony forming cells in murine brucellosis: relationship to immunopathology.

Intravenous injection of mice with Brucella abortus vaccine strain 19, results in a chronic infection, immunity to which is dependent on T cell activation of the macrophages. A major feature of the infection is splenomegaly characterized by massive numbers of macrophages. We report here investigations of the haemopoietic precursors of macrophages, the colony forming cells (CFC), and the growth factors, colony stimulating factors (CSF), controlling their production. Comparison was made amongst three mouse strains, CBA, BALB/c and C57B1/10, as well as the F1 (CBA x BALB/c), which differ in the degree of splenomegaly developed and their ability to rid themselves of infection. The proportion of colony forming cells in the spleen peaked 2 to 3 weeks after infection and was higher in those strains which developed stronger splenomegaly. On the other hand there was no relation between colony forming cells and ability to control infection. Serum CSF also peaked 2-3 weeks post infection, with similar titres in all mouse strains studied. Bone marrow exhibited an early loss of total cellularity after infection followed by recovery. There was a sharp peak in the proportion of colony forming cells in the bone marrow 2 weeks post infection. Spleen and bone marrow CFC and serum CSF all returned to normal levels before infection was resolved.