The clinical significance of PNH-phenotype cells accounting for < 0.01% of total granulocytes detected by the Clinical and Laboratory Standards Institute methods in patients with bone marrow failure.

Annals of hematology 2021 Aug

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Small populations of glycosylphosphatidylinositol-anchored protein-deficient (GPI[-]) cells accounting for up to 0.01% of total granulocytes can be accurately detected by a high-sensitivity flow cytometry (FCM) assay established by the Clinical and Laboratory Standards Institute (CLSI method) and have a prognostic value in bone marrow failure (BMF); however, the significance of GPI(-) granulocytes accounting for 0.001-0.009% of granulocytes remains unclear. To clarify this issue, we examined the peripheral blood of 21 BMF patients in whom minor (around 0.01%) populations of GPI(-) granulocytes had been previously detected by a different high-resolution FCM method (OPTIMA method, which defines ≥ 0.003% GPI(-) granulocytes as an abnormal increase) using both the CLSI and OPTIMA methods simultaneously. These two methods detected an "abnormal increase" in GPI(-) granulocytes in 10 patients (48%) and 17 patients (81%), respectively. CLSI detected 0.002-0.005% (median, 0.004%) GPI(-) granulocytes in 7 patients who were deemed positive for PNH-type cells according to the OPTIMA method, which detected 0.003-0.012% (median 0.006%) GPI(-) granulocytes. The clone sizes of GPI(-) cells detected by each assay were positively correlated (r = 0.994, p < 0.001). Of the seven patients who were judged positive for PNH-type cells by OPTIMA alone, five received immunosuppressive therapy, and all of them achieved a partial or complete response. GPI(-) granulocytes detected in BMF patients by the CLSI method should thus be considered significant, even at percentages of < 0.01%. © 2020. Springer-Verlag GmbH Germany, part of Springer Nature.

Citation

Kohei Hosokawa, Ken Ishiyama, Toshiyuki Ikemoto, Chiharu Sugimori, Hideyoshi Noji, Tsutomu Shichishima, Naoshi Obara, Shigeru Chiba, Haruhiko Ninomiya, Mai Anh Thi Nguyen, Yukari Shirasugi, Yoshihiko Nakamura, Kiyoshi Ando, Yasutaka Ueda, Yuji Yonemura, Tatsuya Kawaguchi, Jun-Ichi Nishimura, Yuzuru Kanakura, Shinji Nakao. The clinical significance of PNH-phenotype cells accounting for < 0.01% of total granulocytes detected by the Clinical and Laboratory Standards Institute methods in patients with bone marrow failure. Annals of hematology. 2021 Aug;100(8):1975-1982