The parotid lymph nodes of naive and previously infected
Balb/c mice were studied after, respectively, infection and
re-infection with cercariae of Schistosoma mansoni via
the ears. Schistosomula were able to pass through the lymph
node by following the lymph flow or by penetrating the veins
of the medullary cords. The number of nodal mast cells was
higher from day 2 to 6 of primary infection; and from day 5 to
11 of re-infection. The amount of degranulating mast cells was
significantly higher at day 4 of infection and at day 1 of re-
infection. Eosinophils characterized the nodal inflammatory
processes observed after day 5 in both primarily-infected and
re-infected mice. However, only in the latter the eosinophils
were able to adhere to the larval surface. In primarily-
infected mice, no intranodal larva presented signs of
degeneration. In contrast, in re-infected animals, some
degenerating larvae were found inside eosinophilic
infiltrates. The eosinophils reached the nodal tissue by
migrating through the high endothelial venules and their
collecting veins.
