Enzyme-linked immunosorbent assay for human leukocyte antigen antibody detection and urine protein test recommended for follow-up monitoring after renal transplantation

BACKGROUND: Although the usefulness of posttransplant human leukocyte antigen (HLA) antibody monitoring has been demonstrated, detailed recommendations have not been worked out in its frequency, the type of patients and methods to be used. Enzyme-linked immunosorbent assay is a simple and cost-efficient assay. The urine protein test that reflects renal dysfunction is performed everywhere. We assessed the clinical value of HLA antibody and urine protein monitoring after renal transplantation. METHODS: Serum samples were consecutively collected from outpatients (n=323) in 2004 and in 2006. Because 18 had graft failure and 8 died with functioning graft for 2 years, 297 paired sera were tested for HLA antibody using enzyme-linked immunosorbent assay. Urine protein was determined to be positive when the dipstick protein reaction was+/-or over (20 mg/dL). RESULTS: Total 297 patients were divided according to the change of HLA antibody status. Only patients with all of (i) de novo HLA antibody production, (ii) continuous detection from peripheral blood, and (iii) positive urine protein test had a significantly higher serum creatinine than the others and demonstrated rapid deterioration of Cr (DeltaCr 1.26 mg/dL during 2 years). Negative change of HLA antibody stopped the increase of serum creatinine. CONCLUSION: The status of HLA antibody and urine protein provides useful information on graft prognosis. Although the tempo of graft injury is relatively slow, a yearly routine HLA antibody test for all patients and the attempt to reduce HLA antibody to negative levels is recommended, when HLA antibody is newly detected and urine protein test is positive.