Early diagnosis of rejection of canine pancreas allografts by fine-needle aspiration biopsy

In pancreatic allograft transplantation with bladder exocrine drainage, falls in urinary amylase (UA) levels have been shown to be an earlier marker of rejection than rises in fasting blood glucose levels. Nevertheless, this is often too late for reversal of the rejection process. In an attempt to diagnose rejection earlier, fine-needle aspiration biopsy was correlated with UA and graft histology. Sixteen dogs were given total pancreatic allografts, 10 without immunosuppression and 6 with triple therapy. FNAB and needle-core biopsies were per­formed on days 0, 2, 4, 7, 9, 24, and 30 and/or at functional rejection, defined as a fasting UA level of <5000 IU/L. Cytocentrifuge preparations of the FNABs were evaluated by total corrected increment (TCI) scores. These increased significantly from 1.0 (±0.4; mean ±SEM) 6 days, to 3.0 (±1.2) 4 days before functional rejection. The increase was due to the presence of blast cells and macrophages. The TCI of healthy immu- nosuppressed grafts remained below 1.6 for 30 days after transplantation and was >5.0 when pancreatitis or acute rejection was seen on conventional histology. Minimal histologic change had significantly lower TCI scores than both acute rejection (P<0.01) and pancreatitis (P<0.001). Acute rejection and pancreatitis were distinguished by a significant difference in increments of monocytes/lymphocytes and macrophages. In contrast to FNAB, UA levels did not differentiate minimal change from acute rejection but were a reliable marker of end- stage rejection.