Analysis of T‐cell repertoire and mixed chimaerism in a patient with aplastic anaemia after allogeneic bone marrow transplantation

We analysed 26 T‐cell receptor (TCR) β chain subfamilies (VB) of a patient with aplastic anaemia (AA) who underwent allogeneic bone marrow transplantation (allo‐BMT). The patient developed pancytopenia at d 80. The patient's T cells were skewed in 10 of 26 TCR‐VB on d 83. These TCR‐VB, especially VB15, which were almost entirely CD8‐positive cells, were skewed throughout her clinical course. Chimaerism analysis of the CD8‐positive cells indicated that they were of recipient origin. Therefore, some immune responses induced by the recipient CD8‐positive T cells had an important role in pancytopenia in AA patients after allo‐BMT.