Sensitive measurement of fragmented red cell population using flow cytometry, and its application for estimating thrombotic microangiopathy after stem cell transplantation.
BACKGROUND
Thrombotic microangiopathy (TMA) is one of the lethal complications after hematopoietic stem cell transplantation (SCT). The levels of fragmented red cells (FRCs), thrombomodulin (TM), and factor VIII-related antigen in the blood are the most important markers for estimating TMA. However, the FRC level has been measured by using microscopy and the naked eye; therefore, an improvement in technology to objectively count FRC is necessary.


METHODS
We established a novel technique to sensitively measure FRC as glycophorin A dull-positive small particles using a flow cytometer and estimated its reliability in patients treated with SCT. The blood level of FRC was compared with other clinical data in 257 blood samples in 16 clinical courses after SCT of 15 patients.


RESULTS
Sorted glycophorin A dull-positive small particles morphologically showed FRC. Measured FRC percentage had a weak correlation with serum levels of lactate dehydrogenase (LDH) and total bilirubin but not with TM level, whereas TM showed a weak correlation with the levels of aspartate aminotransferase and LDH. In a patient with fulminant TMA, decrement of the FRC level led to improvement in liver parameters after treatment, presumably due to the rapid clearance of FRC, and increased simultaneously with the levels of LDH and bilirubin by the TMA recurrence.


CONCLUSIONS
Levels of FRC percentage and TM were independent parameters of TMA. This novel technique may be used as a standard methodology in diagnosing TMA.
First Department of Internal Medicine, Niigata University Medical Hospital, Niigata, Japan. tobaken@med.niigata-u.ac.jp
Ken
K
Toba
Junjiro
J
Tsuchiyama
Shigeo
S
Hashimoto
Takafumi
T
Ichida
Kiminori
K
Kato
Kenichi
K
Watanabe
Tatsuo
T
Furukawa
Miwako
M
Narita
Masuhiro
M
Takahashi
Yoshifusa
Y
Aizawa
D000293:Adolescent; D000328:Adult; D002648:Child; D004912:Erythrocytes / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006021:Glycophorins / Q000032:analysis; D006402:Hematologic Diseases / Q000097:blood / Q000473:pathology / Q000628:therapy; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D018180:Thrombomodulin / Q000032:analysis; D013927:Thrombosis / Q000097:blood / Q000175:diagnosis* / Q000473:pathology
D006021:Glycophorins; D018180:Thrombomodulin