Background. The role of CD20+ B cells in renal allograft rejection has been reappreciated. Importantly, recent studies suggest a relation between CD20+ B cell aggregates and poorer clinical outcome. In the present study, we attempted to confirm these early reports in a tightly controlled patient population and to differentiate between scattered infiltrates and clusters of B cells.
Methods. Fifty-four biopsies from renal transplant recipients with acute rejection were immunostained for CD20, CD3, and C4d. All patients received similar immunosuppressive therapy. Response to therapy was defined as a decrease in serum creatinine level within 2 weeks to 125% or less of the value before the clinically diagnosed episode of allograft rejection. Late clinical outcome was defined in creatinine clearance between 8 and 12 months after the episode of acute rejection or in graft failure.
Results and Conclusion. A significant correlation was observed between interstitial infiltrates of CD20+ cells and CD3+ cells (r=0.720, P<0.001) suggesting that if B-cell infiltrates are present during rejection, they occur with T-cell infiltrates in a concurrent fashion. In contrast to previous reports, no relation was found between the number of CD20+ cells, in aggregates or in a scattered interstitial pattern, and response to conventional therapy. Remarkably, CD3+T cell aggregates did predict a favorable renal outcome.