Kappa immunoglobulin light chain polymorphisms and survival after allogeneic transplantation for B-cell malignancies: a potential graft-vs-leukaemia target.

In the human leucocyte antigen (HLA)-matched haematopoietic stem cell transplantation (HSCT) setting, minor histocompatibility antigen (mHA) disparities between recipient and donor can lead to graft-vs-host disease (GVHD) or graft rejection. Graft-vs-leukaemia (GVL) effect is a beneficial T-cell-mediated immune response that can also occur following HLA-matched HSCT. mHAs with tissue expression restricted to cells of the haematopoietic system are particularly relevant as immunotherapeutic targets for destroying malignant cells without inducing GVHD. Therefore, it is important to identify further haematopoietic-restricted polymorphic mHAs, which may have the potential to be used clinically for adoptive immunotherapy. Polymorphic mismatching of minor antigens, such as the B-cell-specific protein, the kappa immunoglobulin light chain (kappa) may play a role in the incidence of GVL and therefore the survival of transplant recipients following transplantation for B-cell malignancies. Polymorphisms in the constant region of the immunoglobulin kappa polypeptide chain have been defined involving single amino acid changes at positions 153 and 191. In this study, 51 HLA-matched B-cell malignancy transplant pairs were kappa typed by polymerase chain reaction and restriction enzyme digestion to investigate the association between kappa allotype disparity and outcome after transplantation. Kappa allotype disparity between transplant pairs may be associated with an increased survival compared with pairs not mismatched for kappa, as kappa mismatched recipients had a higher percentage of complete remissions and a decreased level of relapse in comparison with the nonmismatched recipients. HLA peptide prediction software was used to determine which HLA types were the best binders for kappa peptides. It was observed that patients with tissue types predicted to bind the kappa Km(1,2) peptides had better survival outcomes and no relapse compared with those with tissue types not predicted to bind the kappa Km(1,2) peptides. This study may contribute to the assessment of the clinical role of kappa with regard to the outcome of allogeneic transplantation for B-cell malignancies.