In contrast, the number of ICOS+Tfh cells was not significant, although ICOS/ICOS-L signaling is essential for the generation of Tfh cells, disrupting this interaction or ICOS deficiency limits the development of Tfh cells either in patients or in mice (49), and blocking ICOS alleviates the inflammation of Alternaria- and HDM-induced allergy in mouse models (50). This evidence concerns the gene ICOSLG and allergic disease.