First-degree Relatives of Celiac Disease Patients Have Increased Seroreactivity to Serum Microbial Markers.

Risk of celiac disease (CD) is increased in relatives of CD patients due to genetic and possible environmental factors. We recently reported increased seropositivity to anti-Saccharomyces cerevisiae (ASCA), Pseudomonas fluorescens-associated sequence (anti-I2) and Bacteroides caccae TonB-linked outer membrane protein (anti-OmpW) antibodies in CD. We hypothesized these markers also to be overrepresented in relatives. Seropositivity and levels of ASCA, anti-I2 and anti-OmpW were compared between 463 first-degree relatives, 58 untreated and 55 treated CD patients, and 80 controls. CD-associated human leukocyte antigen (HLA)-haplotypes and transglutaminase (tTGab) and endomysium (EmA) antibodies were determined. One or more of the microbial antibodies was present in 75% of relatives, 97% of untreated and 87% of treated CD patients and 44% of the controls. The relatives had higher median ASCA IgA (9.13 vs. 4.50 U/mL, p < 0.001), ASCA IgG (8.91 vs. 5.75 U/mL, p < 0.001) and anti-I2 (absorbance 0.74 vs. 0.32, p < 0.001) levels than controls. There was a weak, positive correlation between tTGab and ASCA (r = 0.31, p < 0.001). Seropositivity was not significantly associated with HLA. To conclude, seropositivity to microbial markers was more common and ASCA and anti-I2 levels higher in relatives of CD patients than controls. These findings were not associated with HLA, suggesting the role of other genetic and environmental factors.

Microbial Biomarkers in Patients with Nonresponsive Celiac Disease.

BACKGROUND AND AIMS: In nonresponsive celiac disease (NRCD), the symptoms and duodenal damage persist despite a gluten-free diet. Celiac disease patients with persistent symptoms are found to have a dysbiotic microbiota. We thus hypothesized that increased seroreactivity to the serum gluten-sensitive microbial antibodies Saccharomyces cerevisiae (ASCA), Pseudomonas fluorescens-associated sequence (I2), and Bacteroides caccae TonB-linked outer membrane protein (OmpW) is associated with NRCD. METHODS: ASCA, I2 and OmpW were measured in 20 seronegative CD patients with persistent villous damage despite strict dietary treatment (NRCD group). Fifty-eight responsive patients served as CD controls (55 on gluten-free treatment) and 80 blood donors as non-CD controls. RESULTS: At least one microbial marker was positive in 80% of NRCD patients, in 97% of untreated CD and 87% of treated CD patients, and in 44% of controls. NRCD patients had the highest frequency of ASCA positivity (65% vs 52, 20, and 0%, respectively) and also significantly higher ASCA IgA (median 14.5 U/ml) and IgG (32.5 U/ml) titers than treated CD patients (7.0 U/ml, 13.0 U/ml) and non-CD controls (4.5 U/ml, 5.8 U/ml). The frequencies of I2 and OmpW were lower in NRCD than in untreated CD (65% and 45% vs 86% and 59%, respectively), and I2 titers were higher in NRCD (median absorbance 0.76) and untreated (1.0) and treated (0.83) CD than controls (0.32). OmpW was elevated in untreated (1.1) and treated (0.94) CD patients compared with controls (0.79). CONCLUSIONS: Seropositivity and high titers of ASCA are associated with NRCD and might serve as an additional follow-up tool in CD.

Early microbial markers of celiac disease.

BACKGROUND AND GOALS: Seroreactivity against the Saccharomyces cerevisiae (ASCA), Pseudomonas fluorescens-associated sequence (I2), and Bacteroides caccae TonB-linked outer membrane protein (OmpW) has been detected in celiac disease patients with small-bowel mucosal atrophy. Levels of these antibodies decrease during a gluten-free diet, but their functions and time of appearance in celiac disease are not known. We aimed to search for evidence of possible microbial targets of the immune responses in the early-stage celiac disease patients who showed normal small-bowel mucosal architecture at the time of the first investigations, but later on a gluten-containing diet developed mucosal atrophy. MATERIALS AND METHODS: Forty-four cases with proven early-stage celiac disease and normal mucosal morphology were enrolled. Patients' sera were tested for celiac disease antibodies against tissue transglutaminase (tTG-ab), endomysium, and for microbial antibodies against I2, OmpW, and ASCA IgG and IgA isotypes in both at the time of diagnosis and while on a gluten-free diet. RESULTS: Thirty-four (77%) of 44 patients with early-stage celiac disease had elevated serum antibodies to one or more of the antibodies ASCA, I2, and OmpW. Furthermore, 5 of 6 cases negative for both tTG-ab and endomysium showed positivity for the microbial markers. Seroreactivity to ASCA IgA, ASCA IgG, and OmpW decreased significantly during gluten-free diet. CONCLUSIONS: Seroreactivity to different microbial antigens is evident already in patients with early-stage celiac disease. ASCA antibodies seem to be gluten-dependent. The results indicate that the microbial targets might have a role in the early development of celiac disease.

Endomysial antibodies predict celiac disease irrespective of the titers or clinical presentation.

AIM: To investigate the association between serum antibody levels and a subsequent celiac disease diagnosis in a large series of children and adults. METHODS: Besides subjects with classical gastrointestinal presentation of celiac disease, the study cohort included a substantial number of individuals with extraintestinal symptoms and those found by screening in at-risk groups. Altogether 405 patients underwent clinical, serological and histological evaluations. After collection of data, the antibody values were further graded as low [endomysial (EmA) 1:5-200, transglutaminase 2 antibodies (TG2-ab) 5.0-30.0 U/L] and high (EmA 1: ≥ 500, TG2-ab ≥ 30.0 U/L), and the serological results were compared with the small intestinal mucosal histology and clinical presentation. RESULTS: In total, 79% of the subjects with low and 94% of those with high serum EmA titers showed small-bowel mucosal villous atrophy. Furthermore, 96% of the 47 EmA positive subjects who had normal mucosal villi and remained on follow-up either subsequently developed mucosal atrophy while on a gluten-containing diet, or responded positively to a gluten-free diet. CONCLUSION: Irrespective of the initial serum titers or clinical presentation, EmA positivity as such is a very strong predictor of a subsequent celiac disease diagnosis.

Incidence trends of pediatric inflammatory bowel disease in Finland, 1987-2003, a nationwide study.

BACKGROUND: The present study aimed to characterize the incidence of pediatric inflammatory bowel disease (IBD) in Finland and determine its temporal trends. METHODS: The patients' data were based on the database of the Social Insurance Institution. New cases diagnosed with IBD at the age <18 years in Finland between years 1987-2003 were included. Annual incidence rates were calculated per 100,000 pediatric populations (with 95% confidence intervals [CI]). The country is divided into 21 hospital districts and regional differences were evaluated accordingly. RESULTS: The incidence of pediatric IBD increased from 5 per 100,000 in 1987 to 15 per 100,000 in 2003. The average rate of increase was 6.5% per year (95% CI 5.4%-7.5%). The trends were comparable for boys and girls, also by age group. Information on disease subtype was available from 1992 and during this 12-year period the incidence of Crohn's disease (CD) increased from 2-5 per 100,000 and that of ulcerative colitis (UC) from 4-9 per 100,000. CONCLUSIONS: Our results demonstrate a very high incidence rate for childhood IBD and in particular UC in Finland. Furthermore, a rapid increase took place nationwide in the incidence of both CD and UC during the past two decades.

Celiac disease without villous atrophy in children: a prospective study.

OBJECTIVE: To establish whether children who are endomysial antibody (EmA) positive and have normal small-bowel mucosal villous morphology are truly gluten-sensitive and may benefit from early treatment with a gluten-free diet. STUDY DESIGN: Children who were EmA positive with normal small-bowel mucosal villi were compared with children who were seropositive with villous atrophy by using several markers of untreated celiac disease. Thereafter, children with normal villous structure either continued on a normal diet or were placed on a gluten-free diet and re-investigated after 1 year. Seventeen children who were seronegative served as control subjects for baseline investigations. RESULTS: Normal villous morphology was noted in 17 children who were EmA positive, and villous atrophy was noted in 42 children who were EmA positive. These children were comparable in all measured variables regardless of the degree of enteropathy, but differed significantly from the seronegative control subjects. During the dietary intervention, in children who were EmA positive with normal villi, the disease was exacerbated in children who continued gluten consumption, whereas in all children who started the gluten-free diet, both the gastrointestinal symptoms and abnormal antibodies disappeared. CONCLUSIONS: The study provided evidence that children who are EmA positive have a celiac-type disorder and benefit from early treatment despite normal mucosal structure, indicating that the diagnostic criteria for celiac disease should be re-evaluated.

[Chronic inflammatory bowel diseases in children and adolescents]. / Krooniset tulehdukselliset suolistosairaudet lapsilla ja nuorilla.

Chronic inflammatory bowel diseases in children and adolescents Inflammatory bowel disease (IBD) is further increasing in children and adolescents in most Western countries including Finland. The etiologic factors of IBD and possible triggers have remained unclear. The clinical picture in paediatric IBD is more aggressive than in adults and operative intervention is common. Medical therapy is basically in line with the therapy used in adult patients. Optimal treatment is crucial in order to support normal growth and pubertal development. New serological and fecal analyses enhance the diagnostic accuracy and help the screening of the disease. The impact of IBD into the quality of life and psychosocial health has to be considered especially in severe cases.

Enhanced expression of transcription factor GATA-4 in inflammatory bowel disease and its possible regulation by TGF-beta1.

BACKGROUND: Transforming growth factor beta 1 (TGF-beta1) promotes epithelial healing in inflammatory bowel disease. We hypothesized that GATA-4, a transcription factor cooperating with TGF-beta signaling pathway, is upregulated by TGF-beta1 in the inflamed intestinal epithelium. METHODS: Normal and inflamed intestinal samples were subjected to immunohistochemistry for GATA-4/6 and the TGF-beta signaling pathway components Smad2/3/4. Proliferation and apoptosis were analyzed using Ki-67 and in situ DNA 3'-end labeling assays and Bax and Bcl-2 immunohistochemistry. Furthermore, GATA-4 was assessed in intestinal Caco-2 cells stimulated with TGF-beta1, or interleukin-6 and tumor necrosis factor alpha. RESULTS: GATA-4 was detected in only 20% of normal intestinal samples, but was upregulated in corresponding inflamed regions. GATA-6 expression remained unchanged during inflammation. TGF-beta1 and Smad3/4, but not Smad2, were expressed concomitantly with GATA-4 in inflamed bowel mucosa. In intestinal Caco-2 cells, TGF-beta1 upregulated GATA-4 and Smad2/3/4, whereas treatment with control cytokines had no effect. Inflammation was associated with increased epithelial cell apoptosis and the enhancement of Bcl-2, but not Bax. CONCLUSIONS: We surmise GATA-4 expression is upregulated in inflamed intestine correlating with the activation of TGF-beta signaling pathway. We speculate that TGF-beta1 drives GATA-4 expression during intestinal inflammation, these two components cooperating to promote epithelial healing.

Serological responses to microbial antigens in celiac disease patients during a gluten-free diet.

BACKGROUND: Immunoglobulin A (IgA) autoantibodies to tissue transglutaminase (tTG) are commonly used for screening and diagnosing of celiac disease (CD). Seroreactivity for anti-Saccharomyces cerevisiae antibody (ASCA) and bacterial antigens have also been detected in CD patients. The aim of this study was to examine prospectively serologic responses to microbial targets in adult CD patients at the time of diagnosis and during a gluten-free diet (GFD). Further, we wanted to evaluate whether these serologic specificities could provide new tools for the follow-up of CD patients. METHODS: Data on 55 adult biopsy-proven CD patients were available for follow-up study. Upper gastrointestinal endoscopy was performed on all patients. Sera from patients were tested for antibodies to tTG and ASCA and additionally analyzed with IgA enzyme-linked immunosorbent assays to Pseudomonas fluorescens-associated sequence, I2, and to a Bacteroides caccae TonB-linked outer membrane protein, OmpW. RESULTS: At the time of diagnosis, 91% of CD cases were positive for tTG and 49% for ASCA; positive seroreactivity to I2 was found in 86% and to OmpW in 60% of CD patients at the time of diagnosis. The frequency of seropositivity and serum levels of these antibodies decreased during GFD. Moreover, we found that the decline in the serum levels was significant in all of these markers (p < 0.005). Interestingly, we also found that serum levels of ASCA correlated with the grade of mucosal morphology (p = 0.021), as the ASCA serum levels declined in accordance with mucosal healing. CONCLUSIONS: Commensal enteric bacteria seem to play a role in the small intestinal mucosal damage in CD. This was proven by the serological responses to different microbial antigens shown in this study. Serum levels of ASCA, anti-I2, and anti-OmpW antibodies decreased significantly during GFD, indicating that these serologic markers are gluten dependent in CD patients. These specificities could provide new tools in the follow-up of CD patients.

Long-term health outcomes in pediatric inflammatory bowel disease: a population-based study.

BACKGROUND: The long-term sequelae of inflammatory bowel disease (IBD) may differ between children and adults. We evaluated the health status of patients with pediatric onset of IBD and controls in early adulthood. METHODS: A questionnaire on the current health status and disease history was mailed to patients with childhood onset IBD diagnosed during 1987-2003 in 2 university hospitals in Finland. Matched controls were randomly selected from the Population Register Centre. RESULTS: A total of 368 (67%) of the 550 patients and 646 (37%) controls responded (median age 20 years). Ulcerative colitis (UC) was the most common primary diagnosis (58%) reclassified as Crohn's disease (CD) in 8.5%. Of the patients, 80% had been on glucocorticoids at some point (median duration of the disease 8.3 years). One-third of CD patients had undergone intestinal resection. In UC, total colectomy was common (24%). The frequency of joint diseases (5.4% versus 0.2%) and biliary duct diseases (2.7% versus 0.3%) was higher in patients than in controls (P < 0.001). Overall quality of life was decreased in the patients (mean score 5.7 versus 6.0 in controls, P < 0.001). Further, some impediment on adult height and weight was observed among male patients. CONCLUSIONS: IBD in children may have a more aggressive disease course than in adults, since most pediatric patients need glucocorticoids, and abdominal surgery is frequent. At 8 years from diagnosis, most patients have active disease and quality of life is slightly lower than in the rest of the population.

Fecal calprotectin levels and serological responses to microbial antigens among children and adolescents with inflammatory bowel disease.

BACKGROUND: Noninvasive, sensitive, and specific tools for early identification of chronic inflammatory bowel disease (IBD) are needed for clinical practice. The aim was to identify new noninvasive test combinations for characterization of IBD in children and adolescents by comparing serological responses to microbial antigens and fecal calprotectin, a new promising marker for intestinal inflammation. METHODS: Our study included 73 children who underwent endoscopies because of suspicion of IBD. Their sera were tested for antibodies to the Pseudomonas fluorescens-associated sequence I2, a Bacteroides caccae TonB-linked outer membrane protein, OmpW, and anti-Saccharomyces cerevisiae (ASCA). Simultaneously, samples for fecal calprotectin measurements were obtained from 55 subjects. RESULTS: IBD was diagnosed in 60 patients (Crohn's disease [CD] in 18 patients, ulcerative colitis [UC] in 36, and indeterminate colitis [IC] in 6). Thirteen children had a non-IBD disease. Fecal calprotectin levels were elevated (>or=100 microg/g) more frequently in IBD patients (89%, 39/44) compared to non-IBD cases (9%, 1/11, P < 0.001). ASCA antibodies in sera were detected in 67% (12/18) of patients with CD, in 14% (5/36) of the children with UC, and in 50% (3/6) of patients with IC. Seroreactivity for I2 was observed in 42% of the IBD patients, this frequency being higher than in non-IBD cases (7.7% seropositive; P = 0.025). Serum anti-I2 IgA levels (median absorbances) were higher in those with IBD compared to those without gut inflammation (P = 0.039). The combination of the measurements of fecal calprotectin and serological responses to microbial antigens (ASCA, I2, and OmpW) identified 100% of CD patients (sensitivity 100%, specificity 36%, positive predictive value [PPV] 66%, negative predictive value [NPV] 100%) and 89% of UC patients (sensitivity 89%, specificity 36%, PPV 77%, NPV 57%). CONCLUSIONS: Increased levels of serological responses to microbial antigens (ASCA, I2, and OmpW) and fecal calprotectin are evident in both CD and UC patients. The combination of these markers provides valuable, noninvasive tools for the diagnosis of IBD.

Comparison of a novel whole blood transglutaminase-based ELISA with a whole blood rapid antibody test and established conventional serological celiac disease assays.

OBJECTIVES: Serum immunoglobulin A-class tissue transglutaminase (tTG-ab) and endomysial antibody (EMA) tests play a key role in the diagnostic evaluation of celiac disease. Recently, a novel whole blood rapid test based on self-tissue transglutaminase (tTG) was developed for celiac disease case finding. Based on the same principle, a whole blood self-tTG enzyme-linked immunosorbent assay (ELISA), especially applicable to large-scale screening of celiac disease, has been produced. We assessed the value of this new test in celiac disease antibody detection. PATIENTS AND METHODS: The new test uses endogenous tTG found in red blood cells of whole blood in IgA-class tTG-ab measurement by detecting tTG-tTG-ab complexes formed after hemolysis of the whole blood sample. Stored whole blood samples from 150 untreated celiac disease patients and 107 control individuals without celiac disease were evaluated, and the test results were compared with those of the whole blood rapid test, 2 conventional serum-based tTG-ab ELISA tests, and 2 EMA tests. RESULTS: A total of 15 whole blood samples were found to be clotted or dried after storage and were excluded from further evaluation. The whole blood ELISA test had a specificity (98%) comparable to that of the conventional serological tests, the sensitivity (91%) being slightly lower. The test was concordant with the whole blood rapid test in 92% of cases, with 2 serological ELISA tests in 91% and 94% of cases and with EMA tests in 94% and 93% of cases. CONCLUSIONS: Whole blood self-tTG-based testing is accurate in celiac antibody detection, also when an ELISA method is applied. The testing requires no serum separation or external tTG.

Gluten-dependent small bowel mucosal transglutaminase 2-specific IgA deposits in overt and mild enteropathy coeliac disease.

OBJECTIVES: In coeliac disease, immunoglobulin (Ig)A-class autoantibodies against transglutaminase-2 are produced in the small intestinal mucosa, where they are deposited extracellularly. It remains unclear whether positive intestinal transglutaminase-2-targeted IgA deposits in subjects having normal small bowel mucosal morphology are signs of early-stage coeliac disease. We evaluated the gluten dependency of these deposits in overt and mild enteropathy coeliac disease. PATIENTS AND METHODS: All together 48 subjects suspected of coeliac disease but having normal small bowel mucosal villi were enrolled; 28 of them had latent coeliac disease. The remaining 20 having positive intestinal IgA deposits adopted a gluten-free diet before villous atrophy had developed. For comparison, 13 patients with overt coeliac disease and 42 noncoeliac controls were studied. Small bowel mucosal transglutaminase-2-specific autoantibodies were compared with villous morphology, intraepithelial lymphocyte densities, and serum coeliac autoantibodies. RESULTS: Intestinal IgA deposits were seen in all but 1 of the patients with latent coeliac disease, when the morphology was still intact; the intensity of these deposits increased as villous atrophy developed and decreased again on a gluten-free diet. In 20 patients with intestinal IgA deposits in normal villi, the intensity of the deposits decreased with the diet similarly to that seen in patients with overt coeliac disease. Mucosal IgA deposits were seen initially only in 5% of noncoeliac controls and in 8% after extended gluten consumption. CONCLUSIONS: The response of small bowel mucosal transglutaminase-2-specific IgA deposits for dietary intervention was similar in overt and mild enteropathy coeliac disease. Detection of such IgA deposits thus offers a good diagnostic tool to uncover early-stage coeliac disease.

Elevated serum anti-Saccharomyces cerevisiae, anti-I2 and anti-OmpW antibody levels in patients with suspicion of celiac disease.

OBJECTIVES: Expression of anti-Saccharomyces cerevisiae antibodies (ASCA) identifies patients and individuals at risk for Crohn's disease and has also been reported in 40-60% of celiac disease (CD) cases, suggesting a role of host response to enteric microbiota in the development of inflammatory lesions. In this prospective study in patients with suspicion of CD, we evaluate the frequency and association of ASCA to serological responses for other host microbial targets formally associated with Crohn's disease, including the Pseudomonas fluorescens associated sequence I2 and a Bacteroides caccae TonB-linked outer membrane protein, OmpW. METHODS: Small bowel mucosal biopsies were taken from 242 patients with suspicion of CD, their sera were tested for antibodies to tissue transglutaminase (tTG), ASCA, I2, and OmpW. Eighty adult healthy blood donors were used as controls. RESULTS: The diagnosis of CD was confirmed on biopsy in 134 cases. The occurrence of ASCA and I2 positivity was significantly higher in adult CD patients than in patients with non-CD disease. Anti-I2 levels in the sera were significantly higher in adult CD patients than in non-CD disease or the controls and anti-OmpW levels in CD and non-CD patients when compared to controls. Positive seroreactivity to OmpW seemed to increase with age. Of the CD patients, 90% were seropositive for at least one microbial antigen tested. CONCLUSIONS: This study demonstrates a mosaic of disease-related serological responses to microbial antigens in patients with CD. Immune responses to commensal enteric bacteria may play a role in the small intestine mucosal damage in CD.

Incidence of inflammatory bowel disease in Finnish children, 1987-2003.

BACKGROUND: The incidence of inflammatory bowel disease (IBD) has been increasing in Western countries. In younger people, Crohn's disease (CD) predominates over ulcerative colitis (UC), but the finding is not universal. The present study aimed to characterize not only the incidence but also the clinical picture of IBD from 1987 to 2003 in a large pediatric population in Finland. MATERIALS AND METHODS: Data were collected from the patient discharge and medical records at the 2 largest university hospitals in Finland. The study population covered a total of 619,340 children, representing 56% of the children <18 years old in the country. All of the cases diagnosed with IBD from 1987 to 2003 were reviewed. Clinical, endoscopic, and histological data were collected. Incidence rates were estimated based on statistical assumptions. RESULTS: A total of 604 cases with IBD were diagnosed during the 17-year period. All of the patients had undergone endoscopy. The diagnosis was CD in 203 (34%) cases, UC in 317 (52%) cases, and indeterminate colitis (IC) in 83 (14%) cases. The mean annual incidence rate increased from 3.9/100,000 (95% confidence interval [CI] 2.5-5.8) in 1987 to 7.0/100,000 (CI 5.0-9.4) in 2003 (P < 0.001). The majority of cases were 12 to <15 years old (n = 200, 33%). Of the patients, 5.1% were <3 years old and 14% were <6 years old. IC was most common in young children; 29% of all IBD patients <3 years of age had IC. Of the patients, 97% had been followed up until the age 18 in the hospitals after initial diagnosis (median follow-up 3.1 years). Of the patients, 45.2% were initially treated with steroids, whereas 17.8% received immunosuppressive agents at the end of the follow-up. Operations had been performed in 21% of the cases before age 18. The median time interval from the diagnosis to the first operation was 1.8 (range 7.8) years. CONCLUSIONS: The incidence of pediatric IBD almost doubled in Finland from 1987 to 2003. Surgical intervention was common early in the disease course.

Elevated serum anti-I2 and anti-OmpW antibody levels in children with IBD.

BACKGROUND: Bacteria are implicated as important factors in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to seek evidence of possible bacterial targets of the immune response related to IBD in children. METHODS: Seventy-eight children referred to the Department of Paediatrics at Tampere University Hospital on suspicion of IBD were included in the study. Upper and lower gastrointestinal endoscopies with biopsies were performed on all children. Sera from 75 children were tested for antibodies to the Pseudomonas fluorescens-associated sequence I2, a Bacteroides caccae TonB-linked outer membrane protein, OmpW, anti-Saccharomyces cerevisiae, and perinuclear anti-neutrophil cytoplasmic antibodies. RESULTS: The IBD diagnosis was confirmed in 35 children (18 with Crohn's disease [CD], 12 with ulcerative colitis [UC], and 5 with indeterminate colitis [IC]); 43 children were found to have no inflammation in the gut. Forty-three percent (15 of 35) of those with IBD evinced positive seroreactivity to I2 and 46% (16 of 35) to OmpW. In CD, seroreactivity to I2 and OmpW was 50% (9 of 18) and 61% (11 of 18), respectively. Serum anti-I2 and anti-OmpW immunoglobulin A levels were significantly elevated in children with CD in comparison with the non-IBD group (P = 0.007 and P = 0.001, respectively). A combination of OmpW, I2, and anti-S cerevisiae tests identified 94% of CD patients, and a combination of OmpW, I2, and perinuclear anti-neutrophil cytoplasmic antibodies detected 83% of UC cases. CONCLUSIONS: Among children with IBD, strong serological responses to microbial antigens can be found, suggesting that P fluorescens and B caccae antigens have a potential role in the microbiology and immunology of the disease. Furthermore, serologic reactivity to the set of antigens studied here seems to be applicable in the initial differential diagnosis of children with CD and UC.