Monday, September 27, 2010 2:00 PM - American Society for ...

Methods: 272 T cell CDC and FLXM and 269 B cell CDC and FLXM’s were reviewed and the resultscompared to Mean Fluorescent Intensity (MFI) of LSAB Donor Specific Antibody (DSA).Results: DSA MFI’s were grouped into seven levels and are presented in the table below:[table1]Conclusions: From this data there was a very low frequency of positive crossmatches between 0 and 500MFI. At an MFI of 1000-2000, T cell FLXM and B cell FLXM were positive but CDC was still negative.FLXM did not achieve a 90% rate until the 5000-10000 MFI group. It is interesting that even at >15000MFI’s T and B cell CDC crossmatches were positive 62.5% and 77% respectively and B FLXM werepositive 92.3%. It is evident that LSAB can be used to predict FLXM and CDC within specific MFI rangesbut not with 100% accuracy. Comparing LSAB MFI’s to FLXM and CDC can aid in establishing effectivelimits for Unacceptable Antigens. LSAB MFI is useful as a guide for estimating the risk for a positiveFLXM and CDC.45-PDISCREPANT LUMINEX SINGLE ANTIGEN BEAD AND FLOW PRA RESULT IN RECIPIENTAWAITING HEART TRANSPLANT.Cecil L. Rhodes, Ijeoma Okere, Bryna L. Cook, Vijaya Hegde, Alpa Patel, Monica Ramirez, Prakash Rao.NJ Sharing Network Transplant Lab, New Jersey Organ and Tissue Sharing Network, New Providence, NJ,USA.Aim: To address unexpected results between Luminex Single Antigen Beads (LSAB) and Flow PRABeads (FLPRA).Methods: Patient serum with unexpected results between Luminex Single Antigen Beads (LSAB) andFLOW PRA (FLPRA) was tested by Flow Cytometer Crossmatch (FLXM) to confirm result.Results: Potential Heart Recipient MP was negative for both Class I and Class II antibodies by FLPRA butpositive for Class II LSAB. Subsequent testing by LSAB revealed many positive Class II beads with MFI’sranging from 2021 to 9041. Flow Single Antigen Class II Beads confirmed the LSAB result. Most LSABreactions appear as allele specificities with a lack of groups of positive alleles. Reactions that present asallele specificities are not confirmed by additional beads bearing the same antigen,i.e., theDQA1*0201/DQB1*0401 bead was strongly positive with an MFI of 9041 however the DQA1*0201 andDQB1*0401 are found independently on other beads and were both negative (0 MFI). Two flowcrossmatches (FLXM) were performed with donors matched for a positive allele specific DSA. One donorpositive for DRB1*0102 had a corresponding DSA of 4609 MFI. A second donor positive for DRB3*0202had a corresponding DSA of 6969 MFI. Expected crossmatch MCS for the DRB1*0102 and theDRB3*0202 were 100 and 150 MCS respectively, however, B cell FLXM’s were negative in both caseswith a MCS of 0.Conclusions: Reactions between DQA and DQB beads indicate that this antibody is not directed to HLAepitopes or depends on conformational characteristics of the DQ alpha and beta chains. Lack of reactivityby FLXM with normal lymphocytes may be due to cryptic epitopes that are only assessable in denaturedproteins on the beads.Important questions are raised by this data. 1. Are these antibodies relevant to graftsurvival. 2. What other method can confirm Flow Negative Luminex Positive specificities.46-PDETECTION OF DONOR SPECIFIC ANTIBODIES WITH DynaChip TECHNOLOGY: A PILOTSTUDY.Dave L. Roelen, Simone Brand-Schaaf, Marissa van der Linden, Marian Witvliet, Ilias I.N. Doxiadis, FransH.J. Claas. Dept. of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden,Netherlands.Aim: In the recent years many new technologies for HLA specific antibody screening have beendeveloped, among which the DynaChip assay (Invitrogen, UK). This Solid Phase Assay (SPA) makes useof a chip coated with purified HLA antigens of single donors. We have evaluated whether this assay ismore sensitive compared to the complement dependent cytotoxicity assay (CDC) and whether the definedantibodies are clinically relevant.Methods: In total 142 immunized kidney patients, transplanted between 1995 and 2004, with a negativeCDC cross-match (with current and historical sera) were tested. Sera before transplantation were selected