Open AccessFrequency of anti‐bactericidal/permeability‐increasing protein (BPI) and anti‐azurocidin in patients with renal disease
Author(s) -
YANG J. J.,
TUTTLE R.,
FALK R. J.,
JENNETTE J. C.
Publication year - 1996
Publication title -
clinical & experimental immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.329
H-Index - 135
eISSN - 1365-2249
pISSN - 0009-9104
DOI - 10.1046/j.1365-2249.1996.d01-738.x
Subject(s) - proteinase 3 , medicine , immunology , antibody , autoantibody , antigen , anti neutrophil cytoplasmic antibody , cathepsin g , vasculitis , biology , disease , elastase , enzyme , biochemistry
The major subtypes of anti‐neutrophil cytoplasmic antibodies (ANCA) detected by indirect immunofluorescence assay (IFA) are P‐ANCA and C‐ANCA. In patients with vasculitis, myeloperoxidase (MPO) is the major P‐ANCA antigen and proteinase 3 (PR3) is the major C‐ANCA antigen. BPI and azurocidin, which are also called 57‐kD cationic antimicrobial protein (CAP 57) and 37‐kD cationic antimicrobial protein (CAP 37), respectively, have been proposed as less frequent target antigens for C‐ANCA and P‐ANCA. In patients with renal disease, we determined the frequency of antibodies against BPI and azurocidin. By IFA on alcohol‐fixed neutrophils, monoclonal and polyclonal anti‐BPI antibodies produced a C‐ANCA pattern, whereas rabbit anti‐azurocidin antibody produced a P‐ANCA pattern. By ELISA, sera from 229 P‐ANCA‐positive patients, 99 C‐ANCA‐positive patients and 48 ANCA‐negative (by IFA) patients with renal biopsies were tested for reactivity with recombinant human BPI and purified human azurocidin. Of these sera, 17.5% of P‐ANCA, 30.3% of C‐ANCA and 20.8% of IFA‐ANCA‐negative sera were positive for anti‐BPI; and 8.3% of P‐ANCA, 3.0% of C‐ANCA and 8.3% of IFA‐ANCA‐negative sera were positive for anti‐azurocidin. There was no statistical difference in frequency of anti‐BPI between pauci‐immune necrotizing and crescentic glomerulonephritis (NCGN) and other glomerular disease (OGD), and there was a lower frequency of anti‐azurocidin in NCGN samples than in OGD samples. By Western blot, anti‐BPI‐positive sera reacted with a 57‐kD BPI band and anti‐azurocidin‐positive sera with a 29‐kD azurocidin band. In conclusion, there is a low frequency of anti‐BPI and anti‐azurocidin antibodies in ANCA‐positive patient sera; however, this does not correlate with NCGN, which is a marker for ANCA‐associated small vessel vasculitis, and a similar positivity is found in IFA‐ANCA‐negative patients with renal disease. Therefore, serologic detection of anti‐BPI and anti‐azurocidin is not diagnostically specific in patients with renal disease.