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Maladie de CROHN et Anticorps anti Saccharomyces cerevisiae - ASCA

ASCA—NEW MARKER FOR CROHN'S DISEASE!?
R. L. Young, M.D. , Am J Gastroenterol,1998 Nov, 93:11, 2020-2020

Review of: Quinton JF, Sendid B, Reumauz D, et al. Anti-Saccharomyces cerevisiae mannan antibodies combined with antineutrophil cytoplasmic autoantibodies in inflammatory bowel disease: Prevalence and diagnostic role. Gut 1998;42:788-91.

Voir MAJ 2003 : diagnostic biologique des MICI (maladies inflammatoires chroniques du colon)

Serum samples were obtained from patients with Crohn's disease, ulcerative colitis, normal controls, and other patients with diarrhea. Determinations of pANCA and ASCA (an ELISA anti-Saccharomyces cerevisiae mannan antibodies test) were made. The combination of a positive ASCA test and a negative pANCA test yielded a sensitivity (49%), specificity (97%), and positive predictive value (96%) for Crohn's disease. This early study suggests ASCA may be of benefit in helping to diagnose Crohn's disease and may be a marker in helping to delineate ulcerative colitis from Crohn's disease.

This test is not available for clinical use, but we should watch for further multicenter and prospective studies for this ASCA test. We all need help in differentiating tough cases of ulcerative colitis from Crohn's disease.

DIAGNOSTIC ACCURACY OF SEROLOGICAL ASSAYS IN PEDIATRIC INFLAMMATORY BOWEL DISEASE
Ruemmele FM; Targan SR; Levy G; Dubinsky M; Braun J; Seidman EG, Division of Gastroenterology-Nutrition, Department of Pediatrics, Ste-Justine Hospital, University of Montreal, Montreal, Quebec, Canada. Gastroenterology, 1998 Oct, 115:4, 822-9

BACKGROUND & AIMS: Accurate serological assays are desirable for the diagnosis of inflammatory bowel disease (IBD) types in the pediatric age group. The aim of this study was to test the diagnostic accuracy of modified assays for perinuclear (p) antineutrophil cytoplasmic antibodies (ANCAs) and anti-Saccharomyces cerevisiae antibodies (ASCAs) in patients with pediatric ulcerative colitis (UC) and Crohn’s disease (CD) and in those without IBD.

METHODS: With observers blinded to patients’ diagnoses, serum specimens were analyzed for immunoglobulin (Ig) A and IgG ASCAs and ANCAs by enzyme-linked immunosorbent assay. The perinuclear location of ANCAs visualized by indirect immunofluorescence was confirmed by its disappearance after administration of deoxyribonuclease.

RESULTS: IgA and IgG ASCA titers were significantly greater and highly specific for CD (95% for either, 100% if both positive). pANCA was 92% specific for UC and absent in all non-IBD controls. The majority of patients with CD positive for pANCA had a UC-like presentation. Disease location, duration, activity, complications, and treatment with immunosuppressive drugs did not have an impact on the ASCA or pANCA assay results. After resection, UC patients remained pANCA positive, in contrast to patients with CD, in whom ASCA titers decreased toward normal values postoperatively.

CONCLUSIONS: ASCA and pANCA assays are highly disease specific for CD and UC, respectively. These serological tests can assist clinicians in diagnosing and categorizing patients with IBD and may be useful in making therapeutic decisions.

ANTI-SACCHAROMYCES CEREVISIAE MANNAN ANTIBODIES IN FAMILIAL CROHN’S DISEASE.
Sendid B; Quinton JF; Charrier G; Goulet O; Cortot A; Grandbastien B; Poulain D; Colombel JF, Service d’Hépato-Gastroentérologie et Registre des Maladies Inflammatoires du Tube Digestif du Nord-Ouest de la France (EPIMAD), CHRU Lille. Am J Gastroenterol, 1998 Aug, 93:8, 1306-10

OBJECTIVE: Anti-Saccharomyces cerevisiae mannan antibodies (ASCA) are associated with Crohn’s disease. The aim of this study was to determine the prevalence of ASCA in families in which at least two members were affected with Crohn’s disease.

METHODS: A total of 20 families including two (n=15) or more (n=5) patients with Crohn’s disease were tested for ASCA with use of an ELISA method. Overall, 51 affected members, 66 healthy first degree relatives, and 163 healthy control subjects were studied.

RESULTS: ASCA were detected in 35 of 51 (69%) patients with Crohn’s disease and in 13 of 66 (20%) healthy relatives versus one of 163 healthy control subjects (p < 0.0001 and p < 0.001). ASCA-positive relatives were distributed in 12 of 20 families. ASCA were present in eight healthy parents and four healthy siblings. The prevalence of ASCA in relatives did not depend on the ASCA status of affected members.

CONCLUSION: ASCA in 20% of healthy first degree relatives of patients with Crohn’s disease suggest that these antibodies might be a subclinical marker for Crohn’s disease in families. Whether ASCA reflect environmental or genetic factors or a combination of both is unknown.

ANTI-SACCHAROMYCES CEREVISIAE MANNAN ANTIBODIES COMBINED WITH ANTINEUTROPHIL CYTOPLASMIC AUTOANTIBODIES IN INFLAMMATORY BOWEL DISEASE: PREVALENCE AND DIAGNOSTIC ROLE.
Quinton JF; Sendid B; Reumaux D; Duthilleul P; Cortot A; Grandbastien B; Charrier G; Targan SR; Colombel JF; Poulain D, Service d’HÆepato-GastroentÆerologie, HÈopital Huriez, Lille, France. Gut, 1998 Jun, 42:6, 788-91

BACKGROUND: Perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) are a well recognised marker for ulcerative colitis. Antibodies to oligomannosidic epitopes of the yeast Saccharomyces cerevisiae (ASCA) are a new marker associated with Crohn’s disease. AIMS: To assess the value of detecting pANCA and/or ASCA for the diagnosis of ulcerative colitis and Crohn’s disease.

METHODS: Serum samples were obtained from 100 patients with Crohn’s disease, 101 patients with ulcerative colitis, 27 patients with other miscellaneous diarrhoeal illnesses, and 163 healthy controls. Determination of pANCA and ASCA was performed using the standardised indirect immunofluorescence technique and an ELISA, respectively.

RESULTS: The combination of a positive pANCA test and a negative ASCA test yielded a sensitivity, specificity, and positive predictive value of 57%, 97%, and 92.5% respectively for ulcerative colitis. The combination of a positive ASCA test and a negative pANCA test yielded a sensitivity, specificity, and positive predictive value of 49%, 97%, and 96% respectively for Crohn’s disease. Among patients with miscellaneous non-inflammatory bowel disorders, three were ASCA positive and two were pANCA positive. One control was ASCA positive. The presence of ASCA in patients with Crohn’s disease was associated with small bowel involvement.

CONCLUSION: ASCA and pANCA are strongly associated with Crohn’s disease and ulcerative colitis, respectively. Combination of both tests could help the diagnosis of inflammatory bowel disease.
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