Decreased Th2 and increased Th17 response with higher TCR signal strength was observed in CerS2 null CD4+ T cells upon TCR stimulation and the severity of ovalbumin (OVA)-induced asthma was decreased in CerS2 null mice, implicating a pathological role of very-long-acyl chain SLs in asthma. This evidence concerns the gene CD4 and asthma.