Received on November 23, 2006
Accepted on February 15, 2007

Hematology

Chronic Granulomatous Disease (CGD) and Complete Myeloperoxidase Deficiency Both Yield Strongly Reduced Dihydrorhodamine 123 Test Signals but Can Be Easily Discerned in Routine Testing for CGD

¹ University Clinic Carl Gustav Carus, Department of Pediatrics, Dresden, Germany
² Institut für Laboratoriumsmedizin und Pathobiochemie, Berlin, Germany
³ The Children's Memorial Hospital, Chicago, IL
⁴ Valley Medical Center, Lewiston, ID
⁵ Department of Pediatrics, Charite, Berlin, Germany
⁶ Max Planck Institute for Infection Biology, Berlin, Germany
⁷ Department of Haematology, Technische Universität Dresden, Dresden, Germany
⁸ Laboratoires Reunis Kutter-Lieners-Hastert, Luxembourg, Luxembourg

^* To whom correspondence should be addressed. E-mail: roeslerj{at}rcs.urz.tu-dresden.de.

Background:The flow cytometric dihydrorhodamine 123 (DHR) assay is used as a screening test for chronic granulomatous disease (CGD), but complete myeloperoxidase (MPO) deficiency can also lead to a strongly decreased DHR signal. Our aim was to devise simple laboratory methods to differentiate MPO deficiency (false positive for CGD) and NADPH oxidase abnormalities (true CGD).

Methods: We measured NADPH-oxidase and MPO activity in neutrophils from MPO-deficient patients, CGD patients, NADPH-oxidase-transfected K562 cells and cells with inhibited and substituted MPO.

Results: Eosinophils from MPO-deficient individuals retain eosinophilic peroxidase and therefore generate a normal DHR signal. The addition of rhMPO enhances the DHR signal when simply added to a suspension of MPO-deficient cells but not when added to NADPH-oxidase-deficient (CGD) cells. Lucigenin-enhanced chemiluminescence (LCL) is increased in neutrophils from MPO-deficient patients, whereas neutrophils from patients with CGD show a decreased response.

Conclusions: A false-positive result caused by MPO deficiency can be easily ascertained because, unlike cells from a CGD patient, cells from MPO-deficient patients (a) contain functionally normal eosinophils, (b) show a significant enhancement of the DHR signal following addition of rhMPO, and (c) generate a strong LCL signal.