The timing of vaccinations is delayed after ACTH therapy in Japanese infants, because the immune system may be compromised. To determine the duration of the effect on the immune system, researchers at Kurume University School of Medicine and other centers in Japan examined changes in immunity levels before and after ACTH therapy by measurement of white blood cell, lymphocyte, T/B cell, CD4 and CD8 T cell counts. The CD 4/8 ratio, lymphocyte blastoid transformation, and levels of IgA, IgM, and IgG were also measured before, immediately after, and at 1, 3, 6, and 12 months after ACTH therapy. Cortrosyn Z, a synthetic analogue of ACTH, was administered at a relatively low dosage between 0.015 mg/kg/day and 0.00625 mg/kg/day. Lymphocyte counts and CD4 T cell levels were significantly decreased immediately after and at 1 and 3 months after therapy, and they returned to normal but not pretreatment levels at 6 and 12 months. Helper T cells were more depressed than cytotoxic T cells, but immunoglobulin levels did not change after ACTH therapy. 
COMMENT. Lymphocyte and T cell counts are significantly decreased immediately after and at 1 and 3 months after ACTH therapy, and then gradually recover. A delay of vaccinations for 6 months after ACTH therapy, as practiced by 55% of pediatricians in Japan, is justified based on the results of this study. The authors point out that cell counts used are not direct measures of the actual immunological response. Rather, they indirectly reflect the ability of the individual patient to produce antibodies with vaccinations.