Pure red cell aplasia を併発した全身性エリテマトーデスの一例 [in Japanese] A case of systemic lupus erythematosus accompanied with pure red cell aplasia [in Japanese]
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症例は33歳女性．日光過敏，蛋白尿，汎血球減少，抗核抗体，dsDNA抗体陽性よりSLEと診断された．prednisolone 50 mg/日にて治療を開始後，貧血以外の所見は改善した．ハプトグロビン値は回復し溶血は改善したが，網状赤血球は低値，骨髄では赤芽球系は低形成であり，Pure red cell aplasia (PRCA）の合併と診断された．SLEとPRCAはともに免疫学的異常を背景に発症するが，合併は比較的稀である．PRCA患者血清中には造血阻害因子の存在が報告されている他，細胞性因子の関与も報告されている．今回，本症例にて，患者赤芽球系コロニー形成細胞（erythroid colony forming cell: ECFC）および末梢血T細胞を用いて発症機序の解析を行った．患者T細胞は，数依存性に患者赤芽球造血を抑制した．一方，患者血清にて健常者赤芽球造血は促進した．患者血清中には貧血に対応して赤芽球系細胞の増殖促進因子が含まれていたと考えられた．以上より，本症例でのPRCA発症に細胞性免疫の関与が示唆された．<br>
Pure red cell aplasia (PRCA) is a rare cause of anemia associated with SLE. We herein report a case presenting with SLE and PRCA. A 33-year-old woman, who had been suffering from photosensitivity, proteinuria, and pancytopenia, was diagnosed to have SLE. She showed normochromatic normocytic anemia. The serum level of haptoglobin was <10 mg/dl, and Direct Coombs' test was negative. Her reticulocyte count was 0.8%. Her clinical and laboratory features, except for anemia, had recovered in response to 50 mg/day of prednisolone. The serum level of haptoglobin had normalized, but the reticulocyte count remained low. The bone marrow findings revealed erythroid hypoplasia, and she was diagnosed to have PRCA complicated with SLE. No viral DNA of human parvovirus B19 in her bone marrow was detected. The anemia gradually improved following the further use of 50 mg/day prednisolone. In order to disclose the mechanism of PRCA in this patient, we examined the effects of her peripheral T lymphocytes on erythrogenesis, using erythroid colony-forming cells (ECFC) in her peripheral blood. When we co-cultured peripheral T cells and ECFC, her T cells inhibited erythroid colony formation in a dose dependent manner. Several reports have shown the presence of inhibitory factors in SLE patients' serum such as antibodies against erythroid progenitors or erythropoietin, while other reports have shown abnormal T cells that inhibit the growth of erythroid progenitors. Our study suggests that these inhibitory T cells may therefore have played an important role in the pathogenesis of this patient.<br>
- Jpn. J. Clin. Immunol.
Jpn. J. Clin. Immunol. 29(3), 148-153, 2006-06-30
The Japan Society for Clinical Immunology