Effect of immunization on migration of Schistosoma mansoni through lungs

Schistosoma mansoni schistosomula migrate through the lungs of infected mice; peak recovery occurs 6 days following infection. When cercariae were irradiated at 60Cobalt doses of 24 to 64 Kr, the number of schistosomula recovered from lungs 6 days after infection decreased in a dose-dependent fashion. The pattern of lung migration of schistosomes irradiated at 56 Kr prior to infection was similar to that of nonirradiated schistosomes, but greatly reduced numbers were recovered. When mice were immunized by a single infection with 56 Kr attenuated cercariae 6 wk prior to challenge, the pattern of challenge migration through the lungs was altered. The number of schistosomes recovered increased rapidly between 2 and 6 days post-infection, and showed a plateau between 8 and 10 days with peak recovery occurring 10 days post-infection. This peak recovery was reduced in comparison to that of non-immunized mice, but did not account for all of the reduction observed at the adult worm stage.