Abstract
Extract prepared from mouse lymph node was found to be cytotoxic to all tested tumor cells such as MM2, Friend, SR 61, Ehrlich, S 180 and AH-66F. It also lysed the erythrocytes of sheep, guinea pig, rabbit, rat and mouse. The cytotoxic activity of the extract was enhanced in the presence of EDTA. It more efficiently lysed sheep erythrocytes at lower pH, at lower ionic strength and at higher temperature.
The cytotoxic substance termed “cellular lytic factor” (CLF) was demonstrated to be free unsaturated fatty acids. No hemolytic activity could be demonstrated in chloroform-methanol extracts prepared from lymph nodes boiled or lyophilized immediately after extirpation. Both hemolytic activity and free fatty acids appeared in parallel after homogenization. CLF was fixed on the membrane of target sheep erythrocytes and then caused cytolysis. Inhibitory activity against lymph node extract was found in normal mouse serum. The inhibitory activity was recovered in the albumin fraction. CLF inhibitor inhibited CLF activity when it was added prior to the fixation of CLF on target cells.
