B-lymphocyte activation with an extract of Nocardia brasiliensis.

An extract from the pathogenic actinomycete Nocardia brasiliensis was mitogenic for murine lymphocytes. This deoxyribonucleic acid-synthetic response of whole spleen cells peaked after 48 h in culture at concentrations of Nocardia extract ranging from 10 to 200 micrograms/ml. The extract appeared to be a mitogen for B lymphocytes since cultures of spleen cells from congenitally athymic nude (nu/nu) mice and of antithymocyte serum plus complement-treated spleen cells from conventional (+/+) mice responded as well as untreated spleen cells from normal +/+ mice.