IN VITRO TOXICITY OF ENDOTOXIN FOR MACROPHAGES OF YOUNG GUINEA PIGS AND RABBITS

In cultures of explanted spleen, macrophages from guinea pigs 1 to 5 days old resembled adult macrophages in appearance, numbers of migrating cells, and sensitivity to endotoxin. Macrophages migrating from explants of spleens from newborn rabbits varied greatly in number, but were sensitive to endotoxin. Macrophages were sparse in cultures of newborn rabbit lung, were more numerous in cultures of lung from rabbits 4 and 5 weeks old, and were usually found in greatest numbers in cultures of adult tissues. The relative sensitivity of rabbit macrophages to endotoxin in vitro was similar in newborn, young and old rabbits. The results suggest that the relative susceptibility of guinea pigs and rabbits of different ages to endotoxin is not accompanied by differences in the in vitro sensitivity of individual macrophages to endotoxin, but may be related to the state of development of the reticuloendothelial system outside the liver and spleen. © 1968 S. Karger AG, Basel.