Abstract
Macrophage activation syndrome (MAS) /Hemophagocytic syndrome (HPS) is characterized by proliferation of activated macrophages under conditions such as infection(C Clin Infect Dis 2004)lymphoma(Aouba A Am J Hematol 2004), autoimmune disease(Kaneko K Clin Rheumatol 2005), solid organ transplantation(Akamatsu N,Transplant Proc 2006;). There have been several reports of MAS /HPS after hematopoietic stem cell transplantation, involving not only allogeneic,but also autologous transplantation(Sreedharan A Bone Marrow Transplantation,2006). Generally, MAS /HPS is a cytokine-related disorder.But at present, its clinical characteristics remain unknown. We firstly study here the T-cell receptor repertoire diversity and flow cytometric analysis in MAS /HPS after unrelated peripheral blood stem cell transplantation. The CDR3 of TCR Vα and Vβ subfamily genes were amplified in peripheral blood mononuclear cells from the patient with MAS/HPS after unrelated peripheral blood stem cell using RT-PCR for detection of the distribution of TCR Vα and Vβ repertoire, the PCR products were further analyzed by genescan technique for the CDR3 size, to evaluating clonality of the detectable TCR Vα and VβT cells. Lymphocyte subsets in the peripheral blood were detected by monoclone antibody and flow cytometry including T lymphocyte subsets and NK cells. Flow-cytometric analysis showed CD56+ CD16+ cell 68.65% and CD3+ cell 11.79% in the lymphocyte population;CD16+CD69+ cell 68.51% and CD25+CD16+ cell 31.59% in NK cell. In the T lymphocytic subsets, CD25 + CD3+ cell 62%; CD69+CD3+ cell 75.81%; CD25CD4+ cell 0.81%,CD25CD8+ cell 3.48%; CD69CD4+ cell 0.31%, CD69+CD8+ cell 16.86%.The results show that the main activated lymphocytes is NK cell in patient at diagnosed with MAS/HPS. Of interest, it was only after the addition of high-dose IVIG 1g/kg/d for two days (Ostronoff et al BMT2006) to the treatment that MAS remitted. There are 23 Vα and 15Vβ subfamily T cells could be identified in this time, and the clonal expansion T cells could be found in TCR Vα5, 13, 20; TCR Vβ4, 11, 15 and 21subfamilies. Billiau et al (Blood 2005)describes the immunohistochemical findings on liver tissues from 5 children with MAS in the context of a different type of hemophagocytic syndrome (HPS) in liver transplantation. This study is the first directly to substantiates the presumed immunopathogenesis of MAS by documenting in situ expression of IFN-γ+ by activated CD8+ lymphocytes, and of IL-6 and TNF-α+ by hemophagocytosing macrophages, on liver tissues of patients with MAS. We found no evidence of potential infectious, autoimmune or malignant triggers of R-HPS in our patient, despite extensive investigations. We conclued that the skew distribution and clonal expansion of TCR Vα and Vβ subfamily T cells underscore the primary role of T cells in the pathogenesis of MAS/HPS.
62 Selectively depleting host-reactive T cells from peripheral blood stem cell allografts — preliminary results of a feasibility study
