Filarial Parasites Develop Faster and Reproduce Earlier in Response to Host Immune Effectors That Determine Filarial Life Expectancy
(A) Topical injection of recombinant IL-5 (rIL5) resulted in a local subcutaneous increase (p = 0.05, Wilcoxon rank-sum test, n = 5) but no systemic increase in eosinophil recruitment relative to other lymphocyte populations. (B) The addition of rIL5 upon inoculation of infective larvae to BALB/c mice accelerated their growth before their 3rd larval moult, at D7 p.i. (* p = 0.019, unpaired two-tailed t-test; n = 30, no significant effect of mouse). This occurred independently of mouse genetic background as similar data were obtained in BALB/c and in C57BL/6 mice. (C) The depletion of eosinophils by α-CCR3 antibody treatment 24 h before infection resulted in a prolonged reduction of eosinophilia and (D) in a slower larval development that were not rescued by the addition of rIL-5 (p = 0.003, ANOVA and Dunn's multiple comparison post test: ** p<0.01; * p<0.05; n = 19 to 23). None of the treatments affected larval survival (see Figure S2C). Error bars depict s.e.m.