Analysis of heat shock protein 70 as a causal molecule of aplastic anemia

为探讨再生障碍性贫血(AA)的免疫病理生理机制，我们用流式细胞术检测了初治AA患者外周血单个核细胞(PBMC)热休克蛋白72(-HSP)的表达。热处理后其PBMC显示HSP72+细胞比例较高的AA患者可能对环孢素治疗有反应。在其他血液病如骨髓增生异常综合征和溶血性贫血中未检测到HSP72在PBMC中的高诱导性。在再生障碍性贫血患者对环孢素敏感的PBMC中，HSP72主要在T细胞中表达。因此，在治疗前检测外周血单核细胞中HSP72^+细胞似乎有助于预测环孢素治疗的良好反应。接下来，我们从日本其他医院收集了接受抗胸腺细胞球蛋白和环孢素联合免疫抑制治疗的再障患者的PBMC，并测定了HSP72的诱导性。虽然大约40%的…HSP72+细胞在PBMC中所占比例较高，联合免疫抑制治疗效果好与PBMC HSP72诱导率高无相关性。对RBC上HSP72的详细分析表明，除AA患者外，约30%的正常人的RBC上可检测到HSP72^+细胞，其表达仅限于A型和AB型血型的个体。由于正常人A型血红系祖细胞产生的正常红细胞上不能检测到HSP72，所以在红系祖细胞终末分化后，红细胞上可能出现了HSP72。除HSP72外，A型和AB型血型个体的红细胞均表达HSP90。用N-乙酰氨基半乳糖转移酶和UDP-N-乙酰氨基半乳糖处理强迫表达A抗原的O型红细胞未见抗HSP72单抗结合。因此，HSP72的表达似乎是由遗传决定的，尽管它与A抗原的表达密切相关。HSP72在红细胞上的功能和生物学意义尚不清楚。较少

To characterize immune pathophysiology of aplastic anemia (AA), we studied expression of heat shock piotein (-hsp) 72 in peripheral blood mononuclear cells (PBMCs) of untreated AA patients using flow cytometry. AA patients whose PBMCs exhibited high percentages (>30%) of hsp72+ cells after heat treatment were likely to respond to cyclosporine therapy. The high inducibility of hsp72 in PBMCs was not detected in other hematologic diseases, such as myelodysplastic syndrome and hemolytic anemia. Among PBMCs of AA patients responsive to cyclosporine, hsp72 expression was primarily detected in T cells. Thus, detection of hsp72^+ cell in PBMCs before treatments appeared to be useful for predicting a favorable response to cyclosporine therapy. Next, we collected PBMCs of AA patients who later received combined immunosuppressive therapy consisting of antithymocyte globulin and cyclosporine from the other hospitals in Japan, and determined the inducibility of hsp72. Although approximately 40% of … More patients showed high percentages of hsp72^+ cell among PBMCs, there was no correlation between a good response to the combined immunosuppressive therapy and a high inducibility of hsp72 in PBMCs.In some AA patients, hsp72 was detectable not only in the cytoplasm of PBMCs but also on the surface of red blood cells (RB Cs). Detailed analysis of hsp72 on RBCs revealed that in additi9n to AA patients, hsp72^+ cells could be detected on 20-90% of RBCs of about 30% of normal individuals and that its expression was restricted to individuals bearing blood type A and AB.Heat treatments did not influence the expression of hsp72 on RB Cs. Since hsp72 could not be detected on normocytic erythroblasts that were generated from erythroid progenitor cells of a normal individual with blood type A, hsp72 appeared to emerge on RBCs after terminal differentiation of erythroid progenitor cells. Beside hsp72, RBCs of individuals with blood type A and AB expressed hsp90. Binding of anti-hsp72 monoclonal antibodies was not seen in type O RBCs that were forced to express A antigens by the treatment with N-acetyl galactosaminyltransferase and UDP-N-acefyl galactosamine. Thus, the expression of hsp72 seemed to be genetically determined although it is closely associated with A antigen expression. The function and biological significance of hsp72 on RBCs remain to be determined. Less