Late Graft Rejection in Association With T-Large Granular Lymphocyte Expansion of Recipient Origin After Human Leukocyte Antigen–Haploidentical Stem Cell Transplantation: A Case Report

Skewing of the T-cell receptor repertoire in patients receiving rituximab after allogeneic hematopoietic cell transplantation: what lies beneath?

Rituximab is known to affect T cell immune responses. We and others have reported expansions of T large granular lymphocytes (T-LGLs) in lymphoma patients after Rituximab. We report here the immunogenetic profiling of the T cell receptor (TR) gene repertoire in 14 patients who received Rituximab post allo-HCT and explore clinicobiological correlations. All experienced antigenic triggers, CMV, EBV re-activation and chronic GvHD and had been treated with Rituximab. Skewing of TRBV genes was observed: 3 TRBV genes accounted for half of the repertoire. Oligoclonal pattern with expanded clonotypes was common. Patients with oligoclonality exhibited frequently cGvHD. Longitudinal samples in one revealed distinct clonotypes, suggesting clonal drift. T-LGL leukemia of donor origin with mixed chimerism eventually developed. In conclusion, we report development of oligoclonal T-LGLs after Rituximab post allo-HCT, alluding to antigen selection. Persistence of this phenomenon likely reflects strong antigenic stimulation by viruses and/or cGVHD aggravated by Rituximab.

Large granular lymphocytosis after transplantation

Post-transplant lymphoproliferative disorders (PTLD) represent a heterogeneous group of diseases that occur following transplantation. Large granular lymphocytic (LGL) lymphocytosis is one type of PTLD, ranging from reactive polyclonal self-limited expansion to oligo/monoclonal lymphocytosis or even to overt leukaemia. LGL lymphocytosis in transplant recipients may present as a relatively indolent version of the condition and may be more common than reported, but its natural history and clinical course have not been well described, and the lack of a reliable classification system has limited studies on this disease. Patients with unexplained cytopenias, autoimmune manifestations, or unexpected remissions may be mislabelled. The purpose of this review was to evaluate the clinical features, immunophenotypes, etiopathogenesis, diagnosis, outcomes and treatment of post-transplantation LGL lymphocytosis. In conclusion, LGL lymphocytosis is a frequent occurrence after transplantation that correlates with certain procedural variables and post-transplant events. LGL lymphocytosis should be considered in patients with unexplained lymphocytosis or when pancytopenia develops after transplantation. The diagnosis of LGL lymphocytosis requires a demonstration of monoclonality, but clonality does not indicate malignancy. Additional studies are necessary to further delineate the potential effects of large granular lymphocytes in the long-term prognosis of post-transplant patients.