Biological effects of leptospiral lipopolysaccharide to mouse B, T and NK cells

Leptospiral lipopolysaccharides (LPSs) extracted from Leptospira interrogans serovars copenhageni and hebdomadis were tested for the biological effect to mouse B, T and NK cells. Each leptospiral LPS was a potent mitogen for spleen B cells. Activation of the cells was also expressed by polyclonal B cell activation. In contrast, mitogenicity for T cells, induction of interleukin-2 (IL-2) secretion in T cells and increase of tumor-killing activity and chemiluminescence in NK cells were not observed after stimulation with leptospiral LPS. After intravenous injection of leptospiral LPS in mice, the spleen and lymphnodes were examined by histocytochemical technique. Increase of Ig-bearing lymphocytes was recognized while decrease of T cells was observed in the lymphoid organs. Mitogenic response to PHA, Con A and PWM decreased with relation to the T cell depletion. In conclusion, it is apparent that leptospiral LPS possess marked immunological potencies on B cells but not T and NK cells. The biological effects of leptospiral LPS were common ones as LPS but the level was considered to be different from classical LPS such as Escherichia coli LPS.