The production of IL-4 by lymph node cells from mice inoculated with the resistant isolate seven and 12 weeks post-infection was lower than that observed at five weeks post-infection (1.406±0.2616 and 0.6536±0.08217 ng/ml, respectively), but still significantly higher than that observed in animals inoculated with the susceptible parasites (0.135±0.04826 and 0.1071±0.04127 ng/ml; p = 0.0088 and 0.0040, respectively) (Fig. 4B). This evidence concerns the gene IL4 and infection.