The development of IgG4 antibodies is widely known to be T helper type 2 (Th2) and IL-4, IL-13, and IL-10-driven [53, 54], and the IgG subclass of LGI1 encephalitis antibody is definitely IgG4, implying that the enrichment of Th2 cells and Th17 cells in thymoma tissue was crucial for the production of harmful antibodies in LGI1 encephalitis. This evidence concerns the gene IL4 and thymoma.