IN-VIVO INDUCTION OF APOPTOSIS IN MURINE LYMPHOCYTES BY BACTERIAL LIPOPOLYSACCHARIDES

The effect of bacterial lipopolysaccharide (LPS) on the lymphoid organ s in C3H/HeN and C3H/HeJ mice was investigated. In C3H/HeN mice, LPS i nduced apoptosis, characterised by morphological nuclear condensation and DNA fragmentation resulting in thymic atrophy. Similar but less se vere changes were also observed in the spleen and lymph nodes. In C3H/ HeJ mice, only a slight depletion of lymphocyte numbers was observed i n the lymphoid organs. The plasma endotoxin levels were dependent on t he 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 c orrelated well with the development of apoptosis. These findings sugge st that TNF-alpha and corticosterone may play an important role in LPS -induced apoptosis of lymphocytes.