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Circulating Myeloperoxidase May Cause False Negative Findings in the Analysis of Myeloperoxidase Antibodies in Systemic Vasculitis
Author(s) -
HAAPALA A.M.,
SOPPI E.,
HYÖTY H.
Publication year - 1994
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1994.tb03468.x
Subject(s) - myeloperoxidase , vasculitis , systemic vasculitis , serology , antibody , medicine , immunology , pathology , inflammation , disease
In systemic vasculitis reliable detection of myeloperoxidase antibodies (MPO‐Abs) is of great clinical importance in the diagnosis and follow‐up of patients. We have studied whether circulating myeloperoxidase (MPO) could have an effect on MPO‐Ab findings. Serum MPO and MPO‐Abs were measured in 50 healthy individuals, 35 patients and in the follow‐up samples from two patients with Wegener's granulomatosis. Heating the sera at 56°C for 30min reduced the concentration of immunoreactive MPO both in control and patient sera. In 71% of the patient sera heating made initially negative MPO‐Abs detectable. In a few cases with severe vasculitis the antibody findings remained totally negative. These results, together with the data from the follow‐up samples from two patients with Wegener's granulomatosis, revealed that the serological diagnosis of vasculitis may be considerably delayed if only native samples are analysed for MPO‐Abs. These findings are of considerable clinical significance for the interpretation of MPO‐Ab results. Circulating myeloperoxidase affects MPO‐Ab measurements, causing false negative findings in MPO‐Ab assays. Therefore, it is recommended to denaturate circulating MPO by heating the sera before the analysis of MPO‐Abs and to re‐evaluate the cut off‐values.