CD4 and parasitic infectious disease: As part of the innate immune system, eosinophils play a prominent role in parasitic infections and have been confirmed to kill worms and act as antigen-presenting cells (APCs) for the initiation of Th2 immune responses in strongyloidiasis.[20] Recently findings proved that neutrophil and mast cell activation may play another important role in defending against S stercoralis infection.[21] Studies on adaptive immunity in strongyloidiasis have reported that the CD4+ T cell subsets Th1, Th2 and Th17 showed susceptibility or resistance to infection.[22]