H. Maruyama et al., Protective mechanisms against the intestinal nematode Strongyloides venezuelensis in Schistosoma japonicum-infected mice, PARASITE IM, 22(6), 2000, pp. 279-286
Mice infected with Schistosoma japonicum were resistant to the intestinal n
ematode, Strongyloides venezuelensis. The numbers of adult S. venezuelensis
recovered from mice were significantly decreased when infections were give
n from 6 weeks after S. japonicum infection. Larval recovery from the lungs
showed that significant numbers of subcutaneously inoculated S. venezuelen
sis larvae were eliminated by 3 days in S. japonicum-infected mice (P < 0.0
001), while histology revealed that this was associated with massive eosino
philic infiltration in the lungs. In addition, adult S. venezuelensis worms
implanted in the duodenum of S. japonicum-infected mice could not establis
h in the intestine. This failure was associated with mucosal mastocytosis.
Activation of eosinophils and intestinal mast cells was con elated with ele
vated expression of mRNA for interleukin (IL)-3, IL-4, and IL-5 in S. japon
icum-infected mice. Sera from S, japonicum-infected mice recognized S. vene
zuelensis larva antigens as strongly as those from S. venezuelensis-infecte
d mice, although transfer of sera from S. japonicum-infected mice to normal
recipient mice did not protect them from S. venezuelensis challenge infect
ion. It was concluded that the mechanisms for larval killing and adult worm
expulsion of S. venezuelensis in S. japonicum-infected mice were identical
to those seen in infections with S. venezuelensis only.