Quantitative Assessment of T Cell Clonotypes in Human Acute Graft-versus-Host Disease Tissues

Owing to the difficulty in isolating T cells from human biopsy samples, the characteristics of T cells that are infiltratinghuman acute graft-versus-host disease (GVHD) tissues remain largely uninvestigated. In the present study, TCR-β deep sequencing of various GVHD tissue samples and concurrent peripheral blood obtained from transplant recipients was performed in combination with functional assays of tissue-infiltrating T cell clones. The T cell repertoire was more skewed in GVHD tissues than in the peripheral blood. The frequent clonotypes differed from tissue to tissue in the same patient, and the frequent clonotypes in the same tissue differed from patient to patient. Two T cell clones were successfully isolated from GVHD skin of a patient. In a cytotoxicity assay, both Tcell clones lysed patient peripheral blood mononuclear cells, but not donor-derived Epstein-Barr virus-transformed lymphoblastoid cells. Their clonotypes were identical to the most and second most frequent T cell clonotypes in the original GVHD skin and accounted for almost all of the skin-infiltrating T cells. These results suggest that human acute GVHD may result from only a few different alloreactive cytotoxic T cell clones, which differ from tissue to tissue and from patient to patient. The characterization of T cells infiltrating human GVHD tissues should be further investigated.