CD4 and allergic disease: It is believed that GA may affect the regulatory balance of postoperative immune response.[23] Sevoflurane could not only enhance the CD4+ lymphocytes in spleen in mice[24] but also change peripheral blood leukocyte populations and antibody-producing capacity after either one or repeated exposures.[25] Recently, it was also demonstrated that sevoflurane is involved in genetic methylation[26] and histone acetylation[27] in neonatal GA exposure in animals that may explain reducing allergic disease after GA exposure in younger stage of life.