The responses of gastric mucosal mast cells (GMMCs) to infection with coccidian protozoa, Cryptosporidium muris, in mice were examined during primary and challenge infections. Each of three-week old ICR SPF mice was orally inoculated with a single dose of 2 x 10(6) oocysts of C. muris (strain MCR). After oocyst shedding ceased, the mice were orally challenged with a single dose of 2 x 10(6) oocysts of the same species. GMMCs reached a peak on days 20-30 postinoculation (PI) in number, and decreased thereafter. An increase on days 20-30 post-challenge-infection (PCI) was also observed. The mice showed, on the whole, normal profiles of oocyst shedding in droppings. The number of the cells of uninfected control mice remained constant. Judging from the above results, it is suggested that mastocytosis correlate with expulsion of C. muris in primary infection and the defense mechanism of challenge infection.
