T Cell Receptor Excision Circles (trecs) and Kappa-Deleting Recombination Excision Circles (krecs) As Markers of Early T Cell and B Cell Immune Recovery after Haematopoietic Stem Cell Transplantation (HSCT)

Hematopoietic stem cell transplantation (HSCT) is a key therapeutic strategy for a number of hematological malignancies and non-malignant disorders of the hematopoietic system. One of the most important events post SCT is the immune system reconstitution-a process characterized by a considerable dynamic and is critical in promoting overall survival of transplant patients, restoring immune protection from opportunistic infections, and mediating an alloreactive graft-versus-tumor effect against residual malignant disease. T cell receptor excision circles (TRECs) and Kappa deleting recombination excision circles (KRECs) are byproducts of T cells and B cells receptor recombination processes, respectively and can be used in monitoring denovo synthesis of T cells and B cells post SCT. The aim of this study was to determine the role of combined TRECs and KRECs quantitation in follow up of allogenic HSCT patients through testing samples at 1, 3 and 6 months post-transplant as well as their role in predicting outcomes of transplantation. The study was conducted on 32 patients receiving allogenic HSCT from an HLA identical sibling. Combined quantification of TRECs and KRECs in the genomic DNA of peripheral blood mononuclear cells was performed using quantitative real-time PCR using a standard curve. TRECs and KRECs levels were inversely related to age and significantly lower in patients transplanted for malignant diseases than benign diseases (p <0.05). TREC levels could predict relapse as an outcome and graft versus host disease (GvHD) at 6 months posttransplant. In conclusion, age and nature of disease determined TRECs and KRECs levels posttransplant. In addition, monitoring immune reconstitution using combined TRECs/KRECs quantitiation by real time PCR may be informative and could help predict outcomes of transplantation in allogenic HSCT.