IgA anti-endomysial antibodies on human umbilical cord tissue for celiac disease screening. Save both money and monkeys.

Since celiac disease screening by traditional IgA anti-endomysial antibody test is limited by high costs of monkey esophagus commercial kits as well as by rising ethical problems related to the endangered species, the identification of an inexpensive and commonly available substrate for this antibody determination is urgently required. To achieve this goal, we compared the prevalence of IgA anti-endomysial antibodies detected on monkey esophagus with that on human umbilical cord. Fifty-seven (95%) of 60 untreated adult celiacs were positive for these antibodies on monkey esophagus as well as on human umbilical cord. IgA anti-endomysial antibodies, detected on both tissues, were negative in all 200 disease and healthy controls tested, displaying a 100% specificity for gluten-sensitive enteropathy. These data suggest that human umbilical cord can replace monkey esophagus for IgA anti-endomysial antibodies test. Human umbilical cord allows unlimited testing for celiac disease screening on wide series of high-risk subjects, permitting identification of greater numbers of asymptomatic celiac patients with a remarkable saving of money and bypassing the ethical problems related to killing monkeys.

IFL- and ELISA-antigliadin antibodies recognize different antigenic reactivities from those of R1-antireticulin and antiendomysial antibodies.

In order to establish whether antigliadin antibodies, detected by indirect immunofluorescence (IFL-AGA), display the same antibody reactivity as ELISA-AGA or whether they cross-react with reticulin antibodies (R1-ARA and antiendomysial--EmA), sera from 16 untreated coeliac patients were repeatedly absorbed with crude gliadin dissolved in ethanol/water solution. The comparison between antibody activities before and after absorption demonstrated that IFL-AGA and ELISA-AGA are nothing but a single antibody, as both of them completely disappeared or markedly reduced their titre after incubation with crude gliadin. Moreover, AGA reactivity differs from the reactivity of antibodies directed against reticulin, as R1-ARA and EmA titres were not affected by crude gliadin absorption. The absolute absence of cross-reactivity between IFL-AGA and R1-ARA is further confirmed by the removal of the former and persistence of the latter after gliadin absorption in the 9 sera positive for both antibodies. Sera of coeliac patients, therefore, show only two discrete antibody reactivities, one directed to gliadin and the other to reticulin components.

IgA antibodies to jejunum. Specific immunity directed against target organ of gluten-sensitive enteropathy.

Serum IgA antibodies to jejunum (JAB) were found in 78 (96%) of 81 adults and children with untreated celiac disease. Not only did IgA JAB display a significant higher prevalence than IgA antigliadin antibodies (AGA) (72%) in untreated gluten-sensitive enteropathy, but they also allowed us to identify another three celiacs in addition to those detected by IgA antiendomysial antibodies (EmA). Like IgA EmA, IgA JAB persisted at low titer in seven (14%) of 50 celiacs tested after 12 months of gluten-free diet (GFD) despite the regrowth of jejunal villi, whereas IgA AGA disappeared in all these patients consistently with the normalization of intestinal mucosa. IgA JAB and EmA reappearance was close to 100% in the 13 celiacs studied after six months of gluten challenge, while IgA AGA reached the highest prevalence (about 70%) after one month of gluten ingestion without any increase in the following months. All disease and healthy controls were always negative for the three IgA antibodies. Our results prove that IgA JAB and EmA are the best screening tests for active (untreated and on gluten challenge) celiac disease, whereas IgA AGA should be used for monitoring the response to gluten withdrawal. IgA JAB are an expression of a specific immunity directed against the target organ of gluten-sensitive enteropathy, but, before ascribing them a role in the pathogenesis of celiac disease, it should be ascertained whether their production is a primary event leading to jejunal lesions or whether it is a secondary phenomenon due to antigen release from a previously damaged jejunal mucosa.

Correlation between IgA antiendomysial antibodies and subtotal villous atrophy in dermatitis herpetiformis.

Serum IgA antiendomysial antibodies (EmA) were present in 20 (64.5%) of 31 patients with dermatitis herpetiformis (DH) on a normal diet. A significant correlation was found between these antibodies and the severity of gluten-induced jejunum damage. IgA EmA were positive in 19 (86%) of the 22 DH patients with subtotal villous atrophy, in comparison with the positivity of only one (11%) of the nine DH patients with less severe intestinal involvement (partial villous atrophy or mild abnormalities). The specificity of this test for gluten-sensitive enteropathy was 100%, these antibodies being consistently negative in biopsied disease controls showing a normal jejunal mucosa. Moreover, IgA EmA proved to be useful in monitoring the response to gluten withdrawal in DH patients, as these antibodies always disappeared in all the DH cases studied after 1 year of gluten-free diet together with the regrowth of jejunal villi. The strict relationship between IgA EmA and subtotal villous atrophy is more helpful still since the enteropathy present in DH is usually symptomless and therefore difficult to suspect.

IgA subclass antibodies to gliadin in serum and intestinal juice of patients with coeliac disease.

Serum IgA anti-gliadin antibodies (AGA) were positive in 25 (68%) of 37 untreated adults with coeliac disease belonging mostly to IgA1 subclass (88%) and only in a few cases to IgA2 (12%). Antisecretory component IgA AGA were present in serum of seven patients (28%) by immunofluorescence and in nine (36%) by ELISA. The search for IgA AGA in jejunal juice of eight untreated children with coeliac disease was positive in seven cases (88%), with consistent finding of antisecretory component IgA AGA. These antibodies belonged with equal proportion to IgA1 and IgA2 subclasses. This study shows that in intestinal secretions of untreated coeliac disease cases the IgA immune response to gliadin is confined to polymeric anti-secretory component IgA with the same prevalence of IgA1 and IgA2 subclasses, while in serum IgA AGA are largely monomeric, more frequently of IgA1 than of IgA2 subclass, and with a lower proportion of polymeric anti-secretory component IgA (20-36%). The finding of secretory IgA AGA in serum of patients with coeliac disease could result from a spill-over from the intestinal mucosal synthesis into the circulation.

[Class IgA antigliadin antibodies and monitoring of compliance to gluten-free diet in celiac disease]. / Anticorpi antigliadina di classe IgA e monitoraggio della compliance alla dieta aglutinata nella malattia celiaca.

Antibodies to gliadin (AGA), detected by ELISA, were found in the sera of 37 (88%) of 42 patients with untreated adult celiac disease. IgG class AGA showed a higher sensitivity for the diagnosis of celiac disease than IgA AGA, but, while IgA AGA had a specificity of 100% for celiac disease, false positives of IgG class were present in 19% of 37 patients with ulcerative colitis and in 27% of 26 patients with Crohn's disease. Twenty-eight out of our 42 adult celiac patients were tested after 6-12 months of gluten free diet: IgG AGA persisted in 43% of them showing antibody titres lower than those observed in untreated celiac disease. IgA AGA became negative after gluten withdrawal and there was regrowth of jejunal villi in all but 2 adult celiac patients (7%), who continued to present IgA AGA positivity and subtotal villous atrophy. These 2 patients did not comply to the gluten free diet. Our study confirms the specificity of IgA AGA for untreated celiac disease and emphasizes their usefulness in monitoring the compliance with gluten free diet in adult celiac disease.