Figure 1

Trichinella spiralis elicits in its host a T helper 2 (Th2) cell differentiation that inhibits Th1 cell activation and suppresses classically activated macrophage by IL-4, IL-5 and IL-10 actions. In particular the Th2 cytokines IL-4 and IL-13 act as sufficient stimuli for the differentiation of alternatively activated macrophages which effects on the parasite, protected by the nurse cell, are not well known. In the genetically manipulated experimental model, the lack of eosinophils can influence, through different mechanisms, the outcoming Th1 activation and promote consequently classical macrophage activation. In these cells the production of nitric oxide (NO) by their NOS2 enzyme provokes parasite damage and influences the trasmission to the next host.+ = stimulatory pathway - = inhibitory pathway