Water-soluble adjuvants prepared from Mycobacterium smegmatis and human mixed mycobacteria strains C, DT, and PN were found to increase lymphocyte response in one-way mixed-lymphocyte culture and in vitro immuniza

WSA2 from mycobacteria have recently been shown to have potent biological activity ( I , 2, 5). These adjuvants are nontoxic in vitro and may prove useful in amplification of the immune response. Adam et a!. ( 1) reported that water-soluble fractions that were extracted from the myco bacterial cell walls were nontoxic and were capable of increasing circulating antibodies and of inducing delayed hypersensitivity to ovalbumin ( 1). WSA have also been shown to increase the immune response to sheep red cells, 2,4-dinitrophenol-dextran, and 2,4-dinitrophenol-edestin (7) and to viral antigens (2). Evidence for the potentiation of lymphocyte transformation and in vitro immunization by WSA is provided here.