Persistent Clonal Expansion of Vδ3 and Vδ4 T Cells in T-ALL Case with Minimal Residual Disease after HSCT

• Published in: Blood 2014-12, Vol.124 (21), p.5885-5885
• Main Authors: Xu, Ling, Weng, Jianyu, Huang, Xin, Chen, Shaohua, Geng, Suxia, Yang, Lijian, Wu, Suijing, Huang, Suming, Xin, Du, Li, Yangqiu
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V124.21.5885.5885

Analysis of diversity and clonality is an important tool in monitoring reconstitution of the immune system and identificating specific immune reaction clones involved in hematological malignancy individuals who accepted hematological stem cell transplantation (HSCT). We have previously reported the evolution of malignant and reactive γδ+ T cell clones in a case with relapse T-ALL before and after allogeneic stem cell transplantation (allo-SCT) (from 4 weeks to 108 weeks), relapse was discovered with the same TCR Vδ5+ T cell clone at 100 weeks after transplantation, and the patient underwent chemotherapy over the next two months and achieved again remission with minimal residual disease (MRD). We sequentially monitored the clinical and laboratorial features of this T-ALL case. The patient was received three times donor lymphocytes infusion (DLI) at 117, 120 and 124 weeks after HSCT. In 178 weeks after transplantation, the patient underwent relapse again, however, in this time the patient underwent III grade chronic graft versus host disease (cGvHD). We continued to analyze the samples at different time points after HSCT and DLI, the leukemic Vδ5+ T cell clone was detected in most samples, while this clone could not be detected in donor sample (Figure 1). Moreover, we found that a monoclonally expanded TCR Vδ4 which we reported before and it remained detectable in all samples post transplantation, interesting same monoclonal Vδ4 clone was identified in sample from donor which was collected at time for DLI. The sequence of Vδ4 was confirmed as same TCR rearrangement: Vδ4Dδ3Jδ1, and the expression level of Vδ4 was significantly increased at the time of disease relapse, the Vδ4 expression level in samples from PBMC and bone marrow at different time point was showed in figure 2. The monoclone Vδ4 from donor was thought as specifically expanded for unknown antigen (maybe for virus or leukemia) and may possess cytotoxicity in donor, however, the persistent expansion of Vδ4 in receptor was thought that might be responsible for leukemic cells, virus infection or cGvHD, it remains an opne question. Because patient underwent III grade cGvHD, and whether this Vδ4+ T cell clone was mainly associated with cGvHD, it is needed further investigation. In addition, the clonally expanded Vδ3 with same size was also detected at time before HSCT, and most time points after HSCT, while it could not be identified in donor sample (Figure 3). Obviously, this expanded Vδ3+ T cell clo