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

Results: Analysis of HLA A/B and Cw immunogenicity. Table 1 shows that ratio of anti-HLA A/B ismuch higher than anti-Cw (p=0.0002). The previous transplant has higher chance to generate anti-A/B(p=0.014) and has no difference to generate anti-Cw (P = 0.2821).[table1]Analysis of HLA DR/DQ and DPimmunogenicity. Table 2 shows that DP is a weaker stimulator than DR/DQ (P = 0.0001). Previoustransplant has higher chance to generate anti- DR/DQ (P = 0.0001). Anti-DP is associated with the previoustransplant (P = 0.025).[table2]Conclusions: Based on this study, HLA A/B and DR/DQ have higher immunogenicity than Cw and DP.The previous transplant is a stronger stimulator to generate anti -A/B and DR/DQ antibody. Anti-Cw is notassociated with previous transplant but Anti-DP is associated with previous transplant.32-PDO WE REALLY KNOW EVERYTHING ABOUT CROSS MATCH (OR DOES IgG SUBTYPEMATTER)?Andrew L. Lobashevsky, Kevin Rosner, William Goggins, Nancy G. Higgins. HLA Laboratory, ClarianHealth Transplant Center, Indianapolis, IN, USA; Medicine, Histocompatibility Laboratory, IndianaUniversity, Indianapolis, IN, USA; Department of Surgery, Indiana University, Indianapolis, IN, USA.Aim: Preexisting donor-specific antibodies (DSA) play a critical role in the success of solid-organtransplantation. Strong anti-HLA class II DSA in three transplant candidates (TC) constantly producedpositive B cell Flow Cytometry (FC) cross match (CM) (MCS > 380), whereas CDC CM tests were alwaysnegative. This study was carried out to investigate this paradox.Methods: SAB LUMINEX technology was used to determine the IgG class II antibody subclasses. Thehuman IgG-specific secondary antibodies conjugated to PE were replaced with antibodies specific forhuman IgG1, IgG2, IgG3, and IgG4 subclasses conjugated to the same fluorochrome.Results: IgG solid-phase subtype analysis showed that 26%-86% of DSA were represented bynoncomplement binding IgG2/IgG4 subtypes.[table1]Furthermore, the MFI values of DSA of IgG1/IgG3subtypes were always below the cut off producing positive CDC CM. These findings account for antibodymediated rejection free post-transplant course in these TCs, despite the high level of DSA.Conclusions: Routine application of SAB IgG subtype assay may provide new insights regardingtransplantation in TCs presenting with negative B-cell CDC and positive FC CM.33-PA STATISTICAL TEST FOR SIGNIFICANCE OF CHANGE OF NORMALIZED MFI IN THELUMINEX SINGLE ANTIGEN TEST.Alan M. Luger 1 , Melissa Steele 1 , Bin Ge 2 . 1 Histocompatibility Laboratory, Jewish Hospital, Louisville, KY,USA; 2 Biostatistics, University of Missouri, Columbia, MO, USA.Aim: We present a statistical test of significance of changes in normalized MFI between runs in order toprovide clinicians with valid information about the effectiveness of desensitization of candidates fortransplantation.Methods: An aliquot of a serum from a sensitized patient was included in 23 consecutive runs of the assay.We rejected runs where positive and/or negative controls were unacceptable. In consultation withbiostatisticians we developed rules for decisions:• Outliers were removed using Grubb’s test. We calculated Spearman correlation coefficient between themeans of each test and corresponding standard deviation of each test to examine the relation between meanand SD. Results showed that the mean is positively correlated with SD (For Class 1: r=0.9255, p