Subtypes of immunoglobulin (Ig)-G antibodies against donor class II HLA and cross-match results in three kidney transplant candidates

Preexisting donor-specific antibodies (DSA) play a critical role in the success of solid-organ transplantation. Cross-match (CM) between donor lymphocytes and recipient serum is a pivotal methodology for detecting these antibodies. Luminex platform based solid-phase methodology for anti-human leukocyte antigen (HLA) antibody analysis has revolutionized the approach to antibody detection and HLA specificity identification. In this study, we have reported three cases of successful living donor kidney transplantations performed against strongly positive B lymphocyte flow cytometry (FC) CM owing to highly reactive DSA directed to HLA class II. IgG solid-phase subtype analysis showed that more than 50% of these antibodies were represented by non-complement binding IgG2/IgG4 subtypes. These findings account for antibody mediated rejection (AMR) free long-term post-transplant course in these patients despite, the high level of DSA. Thus, we conclude that routine application of single HLA-coated beads (SAB) IgG subtype assay may provide new insights regarding transplantation or desensitization of patients presenting with negative B-cell complement dependent cytotoxic (CDC) and positive FC CM.