Graft Immunocomplex Capture Fluorescence Analysis Can Detect Intragraft Anti–Major Histocompatibility Complex Antibodies in Mice Cardiac Transplant

Abstract Background Immunocomplex capture fluorescence analysis has recently been applied as a method for detection of intragraft donor-specific anti–major histocompatibility complex (MHC) antibodies (DSA) in humans. Although intragraft DSA in humans is an intense topic of investigation, there is no report to assess intragraft DSA in murine organ transplantation. Methods A model of presensitized mouse cardiac transplantation by donor splenocyteswas used. To capture mouse MHC, anti- MHC class I/II antibodies were immobilized on Luminex beads. The MHC/DSA complexes were captured by the Luminex beads followed by detection of phycoerythrin-conjugated antimouse IgG antibodies where DSA had already reacted with the allograft in vivo. Results Luminex beads were capable of detecting class I DSA in the cardiac allograft, though results for class II DSA were negative. Immunohistochemical investigation revealed that cardiac allografts had abundant MHC class Iexpression but only minor expression of MHC class II. Furthermore, MHC/class IIDSA complexes were successfully detected in splenocytesand serum from a presensitized recipient. Conclusions These data suggested that graft immunocomplex capture fluorescence analysis can be also applied in murine cardiac transplantation. This novel application in mice would accelerate our comprehension of DSA through mechanistic studies.