In-vivo induction of apoptosis in murine lymphocytes by bacterial lipopolysaccharides.

The effect of bacterial lipopolysaccharide (LPS) on the lymphoid organs in C3H/HeN and C3H/HeJ mice was investigated. In C3H/HeN mice, LPS induced apoptosis, characterised by morphological nuclear condensation and DNA fragmentation resulting in thymic atrophy. Similar but less severe changes were also observed in the spleen and lymph nodes. In C3H/HeJ mice, only a slight depletion of lymphocyte numbers was observed in the lymphoid organs. The plasma endotoxin levels were dependent on the LPS dose regardless of mouse strain. On the other hand, the plasma TNF-alpha levels were significantly elevated in C3H/HeN mice 1 h post-injection and the time course of plasma corticosterone concentration correlated well with the development of apoptosis. These findings suggest that TNF-alpha and corticosterone may play an important role in LPS-induced apoptosis of lymphocytes.