Diagnosing antibody-mediated rejection

Antibody-mediated rejection (ABMR) is a serious problem for kidney allografts. While T cell-mediated rejection (TCMR) can be treated effectively with immunosuppressive drugs, ABMR tends to be more refractory to treatment. On diagnostic front, there is a lack of test with sufficient sensitivity and specificity. Diagnostic criteria for ABMR was set by Banff include histologic changes, C4d in graft and donor specific antibody (DSA). The criteria have been proven to be too rigid with the increasingly-recognized C4d negative ABMR.


While newer diagnostic procedures are being evaluated, Sis et al. developed an algorithm from the well-known microcirculatory inflammation: glomerulitis and peritubular capillaritis. The sum of these two Banff score (g + ptc) was shown to a better predictor of DSA than C4d, especially in late grafts. In earlier grafts, sum score >1 can be seen in non-ABMR conditions such as TCMR or ATN. It was also associated with poor/reduced graft survival independent of time, transplant glomerulopathy and C4d.
My note is that the study used g + ptc score to predict DSA, not ABMR itself. Recalled that Banff still uses the 3 criteria for ABMR diagnosis. The presence of DSA itself is not indicative of poor graft survival in the absence of other histologic findings associated with ABMR. This reflects the fact that there is still no gold standard for diagnosing ABMR. Sum score can be used as an indication to test for DSA.