Table 1. Inclusion criteria for eligible patients.

1. Age ≥ 1 year old.

2. Negative or borderline antibody titers against measles, rubella, varicella or mumps.

3. Under treatment with one or two immunosuppressive agents (CsA, Tac, MMF, MZR, AZP, EVR or MTX).

4. Normal cellular immunity

CD4 cell counts ≥ 500/mm3

Normal lymphocyte blast transformation by PHA (stimulation index ≥ 101.6)

5. Serum IgG level ≥ 300 mg/dl

6. No steroid use or prednisolone < 1 mg/kg/day or < 2 mg/kg/2 days

7. Trough levels of tacrolimus < 10 ng/ml

Trough levels of cyclosporine < 100 ng/ml

8. Under good control of primary disease.

9. Difficult to discontinue immunosuppressants because of primary disease.

10. Written informed consent was obtained from patients or families.

CsA, cyclosporine; Tac, tacrolimus; MMF, mycophenolate mofetil; MZR, mizoribine; AZP, azathioprine; EVR, everolimus; MTX, methotrexate; PHA, phytohemagglutinin.