The subgroup analysis did not show significant alteration in IL-4 levels in both infectious (SMD, 2.73; 95% CI, -1.35–6.80; P = 0.19) or autoimmune encephalitis (SMD, 0.50; 95% CI, -0.89–1.90; P = 0.48). Here, IL4 is linked to autoimmune encephalitis.