Antineutrophil cytoplasmic antibodies (ANCAs) in patients with inflammatory bowel disease show no correlation with proteinase 3, lactoferrin, myeloperoxidase, elastase, cathepsin G and lysozyme: a Singapore study.
BACKGROUND
The pathogenic importance of antineutrophil cytoplasmic antibodies (ANCAs) in inflammatory bowel disease (IBD) is unclear and target antigen localisation studies may lend insight to the specific pathogenic mechanisms of IBD. In this pilot study, we looked at occurrence of ANCA in Asian IBD patients. In ANCA-positive samples, we analysed for the presence of target antigens i.e. proteinase 3, lactoferrin, myeloperoxidase, elastase, cathepsin G and lysozyme.


METHODS
This prospective study was carried out from July 1997 to February 1998. Sera were screened for ANCAs with indirect immunofluorescent test and tested with an enzyme immunoassay (ELISA) kit which provides a semi-quantitative assay for human IgG autoantibodies against 6 antigens: proteinase 3, lactoferrin, myeloperoxidase, elastase, cathepsin G and lysozyme.


RESULTS
A total of 75 patients were studied: 50 with IBD and 25 controls with functional bowel disease. Ten had Crohn's disease (CD) and 40 had ulcerative colitis (UC). There was no racial predilection among the Chinese, Malays or Indians. In CD, 1 was positive for cytoplasmic ANCA (cANCA) and 2 for perinuclear ANCA (pANCA). In UC, 4 were positive for pANCA, 15 for atypical perinuclear ANCA (apANCA) and 1 for cANCA. In the CD and UC population, the proportion positive for ANCA was 30% and 50%, respectively. There was no ANCA detected among the controls. Of those ANCA-positive IBD patients (n:23), only 1 demonstrated anti-myeloperoxidase antibodies. No antibodies were detected against the other 5 antigens tested.


CONCLUSIONS
This pilot Singapore study concludes that there is no significant ANCA association with proteinase 3, lactoferrin, myeloperoxidase, elastase, cathepsin G and lysozyme.
Ooi
C J
CJ
Department of Gastroenterology, Singapore General Hospital, 1 Hospital Drive, Singapore 169608. gm2ocj@sgh.gov.sg
Lim
B L
BL
Cheong
W K
WK
Ling
A E
AE
Ng
H S
HS
D000328:Adult; D000368:Aged; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis*; D056649:Cathepsin G; D002403:Cathepsins / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000175:diagnosis* / Q000276:immunology*; D007781:Lactoferrin / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009113:Muramidase / Q000032:analysis; D053146:Myeloblastin; D010196:Pancreatic Elastase / Q000032:analysis; D009195:Peroxidase / Q000032:analysis; D010865:Pilot Projects; D011379:Prognosis; D011446:Prospective Studies; D012016:Reference Values; D012680:Sensitivity and Specificity; D012697:Serine Endopeptidases / Q000032:analysis; D012846:Singapore
D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D009195:Peroxidase; D009113:Muramidase; D002403:Cathepsins; D007781:Lactoferrin; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase; D053146:Myeloblastin