Effect of A. laidlawii on murine and human lymphocyte cultures.

Heat-inactivated A. laidlawii (AL) was found to be a potent mitogen for mouse spleen cells. Spleen cells from homozygous nude mice and spleen cells treated with anti-theta serum and complement responded as well as their respective controls, indicating that AL represented a B-cell mitogen for mouse spleen cells. Spleen cells from LPS-unresponsive C3H/Hej mice responded well to AL. The peripheral blood leucocytes from unselected human donors were also stimulated by AL, which appeared to represent a T-cell mitogen for human leucocytes. However, the possibility that it acted as a specific antigen could not be excluded. Attention was drawn to the possibility that the presence of mycoplasma might considerably affect the results of tests where tissue-culture cells or derivatives thereof are added to leucocyte cultures.