Increased beta 2-microglobulin (B2M) is useful in the detection of post-transplant lymphoproliferative disease (PTLD)

This study examines whether changes in beta 2-microglobulin (B2M) serum levels are useful in the early detection of post-transplant lymphoproliferative disease (PTLD). Serum B2M is monitored daily post-transplant at our center as a marker of change in lymphocyte activation. We identified 16 cases (16/1359; 1.2%) of PTLD from among 1359 kidney and kidney-pancreas transplants. Those with CNS lymphoma (two patients) and titer change only (one) were not included in this review. Thirteen patients had serum titer and clinical evidence of EBV activity; 12 of these patients had histological evidence of PTLD (lymph node 6, kidney 3, and generalized disease 3). Three patients died with disseminated PTLD infection. Nine are alive but only two have the original transplant kidney. All patients received quadruple immunosuppression for induction, and 11 were subsequently treated with OKT3 or ALG for rejection. The mean number of days of induction ALG therapy was 14.8 d (20 mg/kg/d). The mean number of days of OKT3 therapy for rejection was 14.4 d (5 mg/d). During rejection the highest mean creatinine level was 6.8 mg/dL, and the highest mean B2M level was 16.4. With PTLD, the highest mean creatinine level was 7.0 mg/dL and the highest mean B2M level was 32.3 mg/L. The difference in creatinine levels was not significant, but the difference in B2M levels was significant (p < 0.01). We conclude that B2M levels are useful markers in differentiating rejection from PTLD.