P222 Study of complement fixing anti-HLA antibodies tests for C1q C3d, and single antigen tests from different vendors and its application to risk stratification of transplant outcomes

Abstract

Aim Since the main cause of graft failure is the presence of complement fixing anti-HLA antibodies in transplanted patients’ serum, early detection is necessary for risk stratification to predict allograft failure. We conducted a comparative study of two commercial kits to detect complement fixing antibodies and two IgG single antigen tests provided by different vendors. In this study we aimed to determine the behavior of the two kits for IgG detection and to investigate the clinical application of C3d, C1q in patients monitoring. Methods We tested 20 serums for IgG class I and II assay and C3d, C1q with Luminex technology (two differens vendors). All samples were heat pretreated to remove the prozone effect. Results Among the 20 patients analized, for class I antibodies 5 were C1q and C3d positive, 7 were negative for both assays and 8 were C1q positive and C3d negative. For class II, 14 were C1q and C3d. Regarding total IgG detection, one of kits detected more specificities with higher fluorescence intensity (MFI) than the other one, both for class I and class II single antibodies. Conclusions In this preliminary study, a difference in the sensitivity of the two kits tested was observed for single antigen detection. Since the antigens present in the beads of the two kits are different, we think that, despite the difference in the MFI detected, it could beuseful to analize the samples with both kits. In order to determine if the discrepancies between the results of C3d and C1q are due to the difference in sensitivity of the kits or if the results can be correlated with a prognostic value, the clinical evolution of the patients is currently under analysis. Download : Download high-res image (101KB) Download : Download full-size image Download : Download high-res image (342KB) Download : Download full-size image