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DESENSITIZATION PROTOCOLS: ANTIBODIES THAT WON’T GO AWAY.
Andrea A. Zachary, PhD, Robert A. Montgomery, MD,PhD, Milagros Samaniego, MD, Matthew Cooper, MD, Renato Vega and Mary S. Leffell, PhD. Baltimore MD, USA, Johns Hopkins University School of Medicine, 21205, Depts. of Medicine and Surgery.

We previously reported from a series of 38 patients that the only antibodies not eliminated by plasmapheresis and CMIVIg treatment were those to antigens encoded by the DRB3, 4 and 5 loci (DRw52, 53, and 51). In a larger study(n=60), we found other donor specifc antibodies(DSA) that were persistent and examined the refractoriness to treatment by specificity. There was a highly significant persistence of DSA to DRw 52,53 or 51 compared to other DSAs (see table). 9 of 10 patient with persistent DRw-specific DSA were + by CDC at the start of treatment while the 2 patients with DSA eliminated were CDC-. However, of other CDC+ patients, 9 of 11 eliminated cI-specific DSA and 6 of 7 eliminated DSA of other cII specificities suggesting that titer alone did not account for antibody persistence. 3 of the patients with persistent DRw-specific DSA also had cI-specific DSA which was eliminated in 2 of these patients. Patients with DRw-specific Abs maintain grafts despite lengthy persistence of Ab (up to 4 years in one patient). Most patients with any persistent DSA had an episode of Ab-mediated rejection. These were usually single events early in the post-Tx course for patients with cI- or cII-specific DSA while patients with DSA specific for DRw51, 52, or 53 often have multipe rejection episodes, later in the post-transplant period, that usually follow an event that upregulates cII expression. Both the refractoriness of the Ab to treatment and the ability to maintain graft function despite persistent antibody may be related to the reduced level of expression of DRw51, 52, and 53.

Ab specificitycIDR or DQDrw51,52,or 53
persistent2210χ2=30.4
eliminated29152P<0.0001