Cell-mediated response at the muscle phase of Trichinella pseudospiralis and Trichinella spiralis infections.

The cell-mediated response in BALB/c mice infected either by Trichinella pseudospiralis or Trichinella spiralis was compared at days 30-50 post-infection (muscle phase). The former species is non-encapsulated, whereas the latter is encapsulated in host muscles. The pattern of response against the two species was similar. Both species elicited T(H)0 or T(H)1/T(H)2 response, with the last one being dominant. Productions of interferon gamma (IFN-gamma), interleukin (IL)-4 and IL-5 were observed after antigenic restimulation of splenocytes from infected mice. No significant difference was observed between the levels of response to concanavalin A (Con-A) by the splenocytes from both infected and non-infected animals. There was a significant increase in serum IgG(1) and IgG(2a). Flow cytometric analysis revealed a marked proliferative response of splenocytes from infected mice to worm antigens, dominated by B (CD19) lymphoblasts. Only a few helper (CD4+) and cytotoxic (CD8+) T lymphoblasts were present. This was confirmed by an up-regulation of CD69, with a dominant expression on B lymphoblasts. In conclusion, the minimal or lack of intense cellular response against T. pseudospiralis in muscles is likely not due to depression of cell-mediated immunity.