Mast cell responses to Hymenolepis microstoma infection in mice.

Murine mast cells (MC) responded strongly to Hymenolepis microstoma infection. Starting day 7 postinfection (PI) and continuing until the end of the experiment (35 days PI), significantly larger numbers of MC were present in both the duodenum and bile duct of infected mice than in uninfected controls. In animals challenged with 5 cysticercoids 2 wk after primary infection, the MC response in the duodenum, but not in the bile duct, was of even greater degree than in naive hosts. The majority of MC in the duodenum of infected and challenged mice were intraepithelial mucosal MC, whereas in the bile duct the majority were connective tissue MC. Hypertrophy of the duodenal submucosa and of the bile duct wall was noticeable in all infected and challenged hosts. Worms in primary infections were not affected by the host response, but none of the worms in the challenge dose became established. It is postulated that the type of MC involved in specific immune response of the host is the intraepithelial MC, whereas the cell type participating in general inflammatory events is the connective tissue MC.