Immunoglobulin deficiency in kidney allograft recipients: comparative effects of mycophenolate mofetil and azathioprine.

Abstract

Mycophenolate mofetil (MMF) has commonly been substituted for azathioprine (AZA) in kidney transplantation and has been shown to have a greater effect on T cell function and also B cell function than AZA. Although immunoglobulin deficiency has been investigated in patients treated with protocols that include AZA, it has not extensively been studied in MMF-based immunosuppressive protocols. To evaluate this effect, we conducted a prospective study and recruited 49 patients. The patients received either AZA- (group 1) or MMF- (group 2) based therapy. A total of 17 patients in group 1 and 24 patients in group 2 completed the study. Immunoglobulin levels were evaluated before and in every month after transplantation for a 6-month period. Total infectious episodes were recorded and evaluated after 6 months in both groups. While no significant differences have been found in group 1, there were significant decreases in IgG, M, and A levels in group 2 after 6 months (IgG: 11.6+/-1.5-6.8+/-2.0 g/L, P<0.0001; IgM: 2.20+/-1.40-1.40+/-1.16 g/L, P=0.02; IgA: 1.40+/-0.70-1.07+/-0.86 g/L P=0.03). Two patients (11.7%) in group 1 and 11 patients in group 2 (45.8%) were found to have at least one low level of immunoglobulin (P=0.03). When the infectious complications were evaluated, the mean number of infection episodes in each patient was 1.3+/-1.6 and 0.5+/-0.7 for the MMF and AZA groups, respectively (P=0.06). Recurrent urinary tract infection developed in eight patients and seven of those were in group 2. In group 2, 7 of 11 patients with low immunoglobulin levels had recurrent urinary tract infection (63%), while no patient who had normal immunoglobulin levels developed any recurrent urinary tract infections (P<0.001). After 6 months, MMF was changed to AZA in these seven patients, who had both recurrent urinary tract infections and low immunoglobulin levels. All but one patient was found to have normal immunoglobulin levels after 3 months of conversion and only two episodes of infection were recorded during this period. We suggest that serum immunoglobulin levels can be monitored in patients taking MMF, and conversion from MMF to AZA may be an alternative for patients with low immunoglobulin levels and recurrent urinary tract infections.