APOPTOSIS AND IN-VIVO DISTRIBUTION AND CLEARANCE OF EOSINOPHILS IN NORMAL AND TRICHINELLA SPIRALIS-INFECTED RATS

We examined apoptosis of eosinophils obtained from normal rats and rat s infected with Trichinella spiralis (T. spiralis). A considerable per centage of normal rats underwent apoptosis within a few hours, however , the apoptosis rate of infected rats was significantly lower. This ra te began decreasing only 12 h after infection, reached its lowest leve l on day 3, and was restored to normal by day 40. We also studied the effects on eosinophil apoptosis of culture supernatants from Concanava lin A-stimulated spleen cells from infected rats and found that supern atants from days 3, 7, and 18 of infection inhibited apoptosis eosinop hils from normal rats. We then examined the distribution and clearance of eosinophils in vivo. In normal rats, the largest numbers of eosino phils were found in the spleen, liver, and bone marrow. In the infecte d rats, however, by day 3, by which time the worms had begun to migrat e, there was a striking increase in these cells in the intestines. In summary, normal eosinophils are unexpectedly sensitive to apoptosis, w hereas infected eosinophils become resistant to this form of cell deat h.