Likewise, the dexamethasone treatment in asthma patients promotes differentiation toward T regulatory cells by a Foxp3-dependent mechanism [16], and when patients, receiving allogeneic lymphocyte transplantation, are treated with glucocorticoid, graft versus host disease is suppressed by expansion of CD4+CD25+Foxp3+ T cells [17]. This evidence concerns the gene FOXP3 and asthma.