혈소판 감소증의 감별진단에 유용한 망상혈소판 백분율의 측정법 = Quantitation of the Percentage of Reticulated Platelets to Diagnose the Cause of Thrombocytopenia

다국어 초록 (Multilingual Abstract)

Background : Since reticulated platelets (RP), known to be newly released from megakaryocytes in the bone marrow into the blood, contain RNA in their cytoplasm, we can detect them by staining RNA remnants with fluorescent dyes and performing flow cytometric analysis. We attempted to search for the best conditions in quantitating the percentage of RP (RP%) to identify causes of thrombocytopenia. Methods : The RP% were measured on venous blood samples collected in EDTA from 63 normal controls and 48 thrombocytopenic patients. The thrombocytopenic patients were divided into two groups according to the causes: hypoplastic and destructive. The RP% was determined by a flow cytometric analysis with anti-CD41a and thiazole orange (TO) as a fluorochrome. Results : In patients with their platelet count less than 50×109/L, the RP% of two patient groups showed a significant difference. The RP% and platelet count were correlated directly in the hypoplastic group, but inversely in the destructive group. According to the results of ROC curve, the best conditions in quantitating RP% to identify the cause of thrombocytopenia was to apply a 2% threshold of TO positivity among gated platelets; its sensitivity and specificity were 93.3% and 83.3%, respectively. w Conclusions : The RP% is considered to be a good marker for differentiating destructive from hypoplastic thrombocytopenia and monitoring of the destructive thrombocytopenic patient having normal bone marrow such as idiopathic thrombocytopenic purpura. For the accurate measurement of the RP%, the condition of 2% TO threshold is considered to be appropriate.

국문 초록 (Abstract)

배경 : 망상혈소판은 골수 거핵세포에서 생산되어 혈중으로 유리되는 가장 미성숙한 혈소판으로 세포질 내에 RNA를 함유하고있으며, 세포내의 RNA를 염색할 수 있는 TO로 혈소판을 염색하여 유세포 분석기를 이용하여 그 수를 측정할 수 있다. 저자들은정상인과 혈소판 감소증 환자를 대상으로 망상혈소판을 측정하고,유세포 분석 조건에 따른 망상혈소판 백분율을 구하여, 혈소판 감소의 원인을 감별진단하는데 있어서 적합한 유세포 분석 조건을찾고자 하였다. 대 상 및 방 법 : 혈액질환이 없고 혈액검사상 혈소판수가 정상인63명을 대조군으로 하고, 혈소판수가 100×109/L 이하로 감소된 환자 48명을 환자군으로 하여 EDTA 혈액 3 mL를 채혈하고, 혈소판수와 망상혈소판을 측정하였다. 환자군은 생성저하군과 파괴증가군으로 나누었다. 망상혈소판은 전혈을 PE로 표지된 항-GPIIb/
IIIa 단클론항체와 형광색소인 TO로 염색한 후 유세포 분석기를 이용하여 측정하였고, RP%는 혈소판수에 대한 TO 양성 혈소판수의 백분율로 정의하였다.
결과 : 혈소판수가 50×109/L 미만으로 감소된 환자들에서 두환자군의 평균 망상혈소판 백분율은 뚜렷한 차이를 보였으며, 각 환자군에서 혈소판 감소 정도에 따른 망상혈소판 백분율은 생성저하군의 경우 혈소판수가 커질수록 증가되었고, 파괴증가군은 혈소판수가 커질수록 감소되었다. ROC 곡선을 이용하여 혈소판 감소
증 환자에서 원인을 감별진단 하기 위한 망상혈소판 백분율의 기준치를 계산해 본 결과, R1과 R2 영역을 함께 취하여 2%의 기준을 적용하는 것이 진단목적의 망상혈소판 백분율의 적용에 합당하였고, 이때의 민감도와 특이도는 각각 93.3%와 83.3%이었다.
결론 : 망상혈소판 백분율은 골수의 혈소판 회전율을 반영하는 좋은 지표로 생각되며, 골수기능이 정상이면서 혈소판 감소가 심할수록 월등하게 증가되므로 혈소판 회전율이 증가된 혈소판 감소증의 진단 및 추적 감시에 유용할 것으로 생각되며, 정확한 측정을 위해서 유세포 분석시 거대혈소판을 배제하면서 2% 정도의
TO 양성 기준을 적용하는 것이 합당하리라 생각된다.

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