INVOLVEMENT OF REGIONAL LYMPH-NODES AFTER PENETRATION OF SCHISTOSOMA-MANSONI CERCARIAE IN NAIVE AND INFECTED MICE

The parotid lymph nodes of naive and previously infected Balb/c mice w ere studied after, respectively, infection and re-infection with cerca riae of Schistosoma mansoni via the ears. Schistosomula were able to p ass through the lymph node by following the lymph flow or by penetrati ng the veins of the medullary cords. The number of nodal mast cells wa s 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 significantl y higher at day 4 of infection and at day 1 of re-infection. Eosinophi ls 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 degene ration. In contrast in re-infected animals, some degenerating larvae w ere found inside eosinophilic infiltrates. The eosinophils reached the nodal tissue by migrating through the high endothelial venules and th eir collecting veins.