Mitogenic Effect of a Water-Soluble Extract of Nocardia Opaca: A Comparative Study with Some Bacterial Adjuvants on Spleen and Peripheral Lymphocytes of Four Mammalian Species

Abstract

A water-soluble extract of Nocardia opaca (NWSE) induced a very strong stimulation of rabbit and mouse spleen lymphocytes and a weak, but significant, increase of thymidine incorporation by human peripheral lymphocytes and monkey blood, or spleen cells. As was demonstrated by the migration inhibition factor assay, the strong mitogenic activity observed with mice spleen cells was not related to a state of natural impregnation. In the same experiments, the various lymphocytes were also incubated with M. smegmatis water-soluble adjuvant (WSA) and S. enteritidis lipopolysaccharide (LPS). No mitogenic activity was shown with WSA even when this extract was incubated with the lymphocytes of human tuberculin responders, showing that this preparation is free of tuberculoprotein contaminants. Finally, it must be noted that, contrary to what is observed in mice, LPS did not induce thymidine incorporation by monkey or rabbit spleen cells.