STUDIES ON RESPONSES OF INTERMEDIATE HOSTS TO INFECTION WITH TAENIA CRASSICEPS (ZEDER, 1800) (CESTODA)

Male and female mice developed a leucocytosis in peritoneal fluid and blood after intraperitoneal injection with cysticerci of Taenia crassiceps. Free mast cells declined intraperitoneally from normal range of 650 to 1500 cells per cu. mm to less than 100 per cu. mm; eosinophils increased from less than 100 per cu. mm to 95,000 per cu. mm, with a logarithmic rise during the first 1 to 2 weeks in mice overcoming the cysticerci. Cells of the monocyte–lymphocyte series also increased intraperitoneally, but heterophils remained scarce. Leucocytosis and eosinophilia were most pronounced in mice just overcoming cysticerci, less when cysticerci were alive, and least when cysticerci were overcome. Males generally developed higher eosinophilia faster than females and overcame cysticerci more successfully. Females which were fed eggs developed peripheral eosinopenia during the first 2 weeks, then changed to an eosinophilia without concomitant leucocytosis. Those mice which develop high eosinophilia quickly overcome injected cysticerci most successfully. Female mice with intraperitoneal cysticerci showed strong resistance against challenge feedings of eggs 28 days later, but were less resistant after only 14 days. Mate and female guinea pigs, which are refractory to intraperitoneally injected cysticerci, developed a blood eosinophilia, and eosinophilia and leucocytosis in the peritoneal fluid. No free mast cells were seen.