| Aplastic Anemia (AA) is a heterogeneous disease characterized by failure of bone marrow hematopoiesis resulting in pancytopenia. Clinically, it is manifested by anemia, bleeding and serious infection.So far, the etiology and mechanism of AA is not clear.It can be devided into two categorys when considering the genetic abnormality of patients: congenital and acquired aplastic anemia. The lalter is subdivided into idiopathic and secondary aplastic anemia. Aquired aplastic anemia is a common disease all over the world and claims many lifes every year. The complexity of the etiology and mechanism of those diseases, the poor response to therapy and low rate of long-term survival made it a concertration of many studiers. The mechanism of AA was very complicated and three hypothesis developed. That is the injury of stem cell, the defect of hematopoietic microenvironment and the immunologic abnormality. In recent yeays,the 6 abnormality of stem cell and immune-mediated suppression of hematopoiesis has been considered the most important mechanism in the development of aplastic anemia, mainly based on high rates of response to immunosuppressive therapy in patients with AA.It is reported that over 70% of patients with AA have abnormally activited immnologic condition. So it is vital in many respect to further study immnologic mechanism of AA. -A We studied the I lymphocyte subset and its clonality of a AA patient ,by using FCM, intracellular cytokine stainnng, RT-PCR and Genescan assay. Then, we further cloned CD34~ cell-reactive T-cell clones in order to research their phenotype and function Results: 1. In CD34~T cells with AA patient, 44.9% is CD4~ and 48.3% is CD8~cell, with thee ratio of CD4/CD8 being 0.93. In control, 47.5% is CD4~cell and 48.49% is CD8~ cell,and CD4ICD8 ratio is 0.98. It is clear that the distribution of CD3~celI are normal in AA patient. 2. 52.9% of CD3~ I cell in AA patient produced IFN-y, 2.3% of I cell produced IL-4, the IFN-y~/IL-4~ ratio is 22.6/1. While in normal control, * IFN-y~/IL-4~ is 8.9/1. We conclude that in patient with AA , The T cells commit an noted balance shift, as a result ,the JFN-y~ I cell is increased. 3. We arnplificated all the 24 Vf3 subfamilies( Vj31-Vf324) transcripts with RT-PCR.We find that like normal control,T lymphcyte in AA patients utilize highly diverse segments of the ICR Vf3 , most V~3 subfamilies are expressed and the level of expression are higher in AA patients than in normal controler.These results manifest the divercity of I cell clone in AA patient. 4. We labled all the 24 VP/C~3 PCR products with a fluorescence Fain, and 7 commited size distribution analysis. We find that the Vj3IC~ PCR products of normal control showed multipeak distribution profile which suggested the T cell distribution is balanced without having dominent T clone. However ,theVi3/Cf3 PCR products of AA patient showed dominent peak distribution of CDR3 especially V~33, VPS and Vp23, which showed the T cell clone that used the Genes of Vf33, V~38 and Vf323 were expanded and had become the dominen...
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