Effect of Nocardia rubra cell-wall skeleton on colony-stimulating activity and myeloid colony formation.

The in vivo effect of Nocardia rubra cell-wall skeleton (N-CWS) was studies on the generation of bone marrow granulocyte-macrophage progenitor cells [colony-forming units culture (CFU-c)] and on the levels of myeloid colony-stimulating activity (CSA) in the conditioned medium of the lung (LCM) and serum obtained from mice. In vitro bone marrow culture showed that intraperitoneal (ip) treatment of mice with N-CWS markedly enhanced CFU-c formation induced by stimuli in LCM or serum derived from lipopolysaccharide (LPS)-treated mice. The LCM and serum of mice injected with N-CWS ip were also prepared and assayed for CSA. CSA levels with N-CWS-LCM as well as LPS-LCM used as the standard CSA were markedly greater than those achieved with control LCM. N-CWS-serum also showed a low but significant level of CSA. The CSA level of N-CWS-LCM was maximal at 3 to 5 days after N-CWS injection. These results raise the possibility that enhanced CSA production might be a major mechanism for N-CWS stimulation of granulocyte-macrophage production.