These specific mechanisms may be through the downregulation of serum IL-18 in PNS children, antagonizing the inhibition effect of hormone on IL-10 and upregulating IL-10, increasing NK and Th cell number, and regulating the balance of Th1/ Th2, to enhance the anti-infection ability of PNS children and reduce recurrence chance. The gene discussed is IL10; the disease is paraneoplastic neurologic syndrome.