Regional and splenic lymphocyte proliferative responses of mice exposed to normal or irradiated Schistosoma mansoni cercariae.

Developing larvae of Schistosoma mansoni migrate through various tissues en route to the liver and mesenteric veins of their definitive host. Regional (lymph node) and systemic (spleen) blastogenic responses to cercarial, adult and egg antigens were measured in CBA/J mice at various times after exposure to normal or irradiated S. mansoni cercariae. Among the separate lymph node groups studied were those draining the tail, thoracic region, intestines, head and neck, and the pelvis. Blastogenic responses were assayed by a micromethod requiring 10(5) cells in 20 microliter volumes per culture. Up to 5 weeks post-cercarial exposure the pattern of responses in lymphoid tissues of infected mice coincided with the migratory route of the parasites. Following oviposition, cellular reactivity was pronounced in all lymph node groups. The reactivity of mice exposed to irradiated cercariae followed a pattern suggestive of a sustained antigenic stimulus only in the nodes draining the tail and lungs. Splenic (systemic) reactivity was roughly comparable between the two exposure groups. These data show the independence and vast differences in the host regional responses following normal or irradiated cercarial exposure.