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#41-OR
FACTORS THAT PREDICT DONOR-SPECIFIC ANTIBODY REMOVAL BY PLASMAPHERESIS AND INTRAVENOUS IMMUNOGLOBULIN.
Velta A. Lazda PhD 1. 1 Histocompatibility Laboratory, Gift of Hope Organ & Tissue Donor Network, Elmhurst, IL, USA .
Desensitization protocols based on the combination of plasmapheresis (PP) and intravenous immunoglobulin (IVIg) are commonly used to desensitize patients who have a positive crossmatch (XM) with their intended living donor in order to transplant the patient. We investigated the reasons why such protocols are effective for some patients but not others. This study includes 31 living donor kidney transplant candidates (74% first transplant candidates; 20 females, 11 males) who were treated with PP and IVIg (100 mg/kg) every other day starting 1 week before transplant in order to remove donor-specific antibody (DSA). Prior to treatment all 31 patients had a positive T-cell flow XM, channel shift (CS) range of +28 to +114 (negative = < +20 CS); 14 patients (45%) also had a positive antiglobulin-augmented complement-dependent cytotoxic (AHG-CDC) T-cell XM. Sera collected after each treatment were crossmatched with the intended donor to test for DSA, and also screened for Class I panel-reactive antibodies (PRA) by CDC, ELISA and Flow. We found that DSA removal was less often successful for patients with a strongly positive (> +70 CS) T-cell flow XM (40%, N=10) vs. those with CS < 70 (81%, N=21), p=0.0401. Also, DSA was less likely to be removed when AHG-CDC XM was positive (36%, N=14) vs. negative (76%, N=17), p=0.0325. There was no significant correlation with other factors examined, such as PRA, previous transplants, donor/recipient demographics, etc. In conclusion, the data presented here suggest that the strength of DSA at the initiation of treatment is a major factor that determines how easily the DSA will be removed and this information can be used to predict the effectiveness of the desensitization protocol.