Expression patterns of B cells in acute kidney transplant rejection.

Objectives: To evaluate B-cell expression patterns and association with function and survival in dysfunctional kidney allografts.

Materials And Methods: There were 110 kidney transplant recipients included who had for-cause biopsies. Demographic and transplant data were collected. Immunostaining for B cells, plasma cells, and C4d was performed by the immunoperoxidase technique in paraffin-embedded samples. Circulating antihuman leukocyte antigen donor-specific antibodies were detected in a single-antigen assay at biopsy. The main outcomes were kidney graft survival and function. The patients were evaluated in 3 groups according to the Banff classification: no rejection (40 patients), T-cell-mediated rejection (50 patients), and antibody-mediated rejection (20 patients).

Results: The CD138-positive plasma cell-rich infiltrates predominated in antibody-mediated rejection and were associated with stronger reactivity against panel antibodies (r = 0.41; P ≤ .001) and positive donor-specific antibodies (r = 0.32; P ≤ .006). The CD20-positive lymphocytes were associated with T-cell-mediated rejection, increased human leukocyte antigen mismatch, and frequency of retransplant. The CD138-positive cell infiltrates also were significantly greater in patients who had late than early rejection. There was no correlation between cellular CD20 and CD138 expression, and neither CD20 nor CD138 predicted worse graft function or survival. Other markers of antibody-mediated rejection such as C4d and donor-specific antibodies were associated with worse graft function and survival at 4 years after transplant. In multivariate analysis, C4d was the only risk factor associated with graft loss.

Conclusions: After kidney transplant, CD20-positive B-cell infiltrates were associated with T-cell-mediated rejection, and CD138-positive plasma cells were associated with antibody-mediated rejection. Graft loss was associated with the presence of C4d.