Autoantibodies pANCA, GAB and PAB in inflammatory bowel disease: prevalence, characteristics and diagnostic value.
BACKGROUND
The diagnosis of inflammatory bowel disease (IBD), particularly the differentiation between ulcerative colitis (UC) and Crohn's disease (CD), is difficult and delayed in many cases, despite invasive diagnostic tools.


OBJECTIVE
To determine the presence and evaluate the diagnostic accuracy of the potential serological diagnostic markers perinuclear antineutrophil cytoplasmic antibodies (pANCA), autoantibodies to intestinal goblet cells (GAB) and autoantibodies to exocrine pancreas (PAB), together with combinations of these, in the diagnosis of IBD and differential diagnosis of UC and CD.


METHODS
The presence of pANCA, GAB and PAB was determined in indirect immunofluorescence assay of serum samples from 71 patients with IBD (CD 43, UC 28) and 41 healthy controls. The antigen specificity of ANCA was determined using ELISA.


RESULTS
Compared with the control group, we confirmed a statistically significant presence of pANCA (71.4%) and GAB (46.4%) in patients with UC and the presence of PAB only in patients with CD (30.2%) (P < 0.001). In healthy controls, neither PAB nor GAB was detected and pANCA was present in only 4.8%. The sensitivity, specificity and positive and negative predictive values in differentiation of IBD from healthy controls were as follows: pANCA(+): 71%, 95%, 91%, 83%; GAB(+): 46%, 100%, 100%, 73%; PAB(+): 30%, 100%, 100%, 58%; combination of (pANCA(+) or GAB(+))/PAB(-): 82%, 95%, 92%, 87%; and to distinguish UC from CD: pANCA(+): 71%, 98%, 95%, 84%; GAB(+): 46%, 98%, 93%, 74%; PAB(+): 30%, 100%, 100%, 48%; (pANCA(+) or GAB(+))/PAB(-): 82%, 98%, 96%, 89%.


CONCLUSIONS
All three autoantibodies may be helpful tools in non-invasive diagnosis and differential diagnosis of UC and CD. Combination of the autoantibodies may be particularly helpful, as the diagnostic sensitivity is considerably improved.
Homsak
Evgenija
E
Department of Laboratory Diagnosis, University Medical Center Maribor, Maribor, Slovenia. evgenija.homsak@ukc-mb.si
Micetić-Turk
Dusanka
D
Bozic
Borut
B
D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D000918:Antibody Specificity / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D003093:Colitis, Ulcerative / Q000175:diagnosis / Q000276:immunology*; D003424:Crohn Disease / Q000175:diagnosis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D020397:Goblet Cells / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007413:Intestinal Mucosa / Q000276:immunology*; D046790:Pancreas, Exocrine / Q000276:immunology*
D019268:Antibodies, Antineutrophil Cytoplasmic; D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G