CD4 and hearing loss disorder: We have also found that up-regulation of the expression of IL-1R2 genes in CD4+ T cells is associated with age-related developments of hearing loss, SG degeneration, and the dysfunction of cellular immunity, and that the rejuvenation of recipient immunity by the inoculation of young CD4+ T cells or a fetal thymus graft leads to down-regulation of the genes in CD4+ T cells and reduces these features of senescence [21].