3.1
#62
PRA AND ALLOANTIBODY SPECIFICITY IN PATIENTS WAITING FOR RENAL TRANSPLANTATION.
S. A. Pesoa, PhD , S. M. Bahamondes, LT , A. I. Borosky, BS and C. M. Vullo, PhD . Cordoba Argentina, LIDMO, 5000, Tissue Typing .

---

We performed PRA and alloantibody specificity analysis of sera from 529 patients .Samples were routinely and quarterly obtained and stored until screened against a panel of 35 HLA typed cells, selected to provide representation of 98% of the HLA A-B-C specificities . PRA screening was performed using the standard NIH-CDC (Amos modification), with and without DTT. The most recent serum available was used for pre-Tx XM against cadaver donor cells (DC). Rigorous recording of priming events was undertaken.
The study revealed that 23, 5 % of patients had anti HLA antibodies. Of these, 20, 5% showed 1-79% PRA and 3% were highly sensitized (≥ 80%). We looked at changes in the PRA over 8 years (1995-2002): PRA negative patients increased slightly as low PRA reactive individuals became negative. Highly sensitized patients remained unchanged.
Antibody specificities were defined in 11% of the sera allowing the identification of patients who will be positive against any specific HLA mismatch.
At last, we analyzed the results obtained when 621 sera, previously screened for PRA, were cross-matched against 81 DC. We found that 98, 4% of the non reactive PRA sera gave negative results . The remaining 1, 6% gave positive results and this was due to the use of AHG-CDC as pre-Tx test ,while 78% of current PRA + sera gave positive results against DC. The use of stored instead of current sera allowed to reduce the working time to 9,10 hs (HLA typing +XM) compared to 16,14 hs ( p=8x10^-12) when waiting for either the patient or the sera was necessary.
In conclusion, careful documentation of priming events and antibody screening of sera would allow the prediction and selective omission of pre –Tx XM for a given donor. The use of these stored sera is associated with a putative reduction in the cold ischemia time.