To examine the main effector subset in MS with high serum Sema4A levels, we compared serum levels of IFN-γ and IL-17A among RRMS patients with high (≥ 2500 U/ml) and low Sema4A levels (< 2500 U/ml). The gene discussed is SEMA4A; the disease is relapsing-remitting multiple sclerosis.