New immunofluorescent blood test for gluten sensitivity

IgA anti-tissue transglutaminase as a diagnostic marker of gluten sensitive enteropathy

AIMS

To compare and contrast the sensitivity, specificity, and positive predictive values of IgA antibodies to guinea pig tissue transglutaminase (ELISA), endomysium, and reticulin (immunofluorescence), and gliadin (ELISA), and IgG antibodies to gliadin and tissue transglutaminase.

METHODS

Sera from 27 newly diagnosed patients with coeliac disease, 65 biopsied gastrointestinal disease controls, and 50 consecutive blood donors were tested. All cases were adults.

RESULTS

IgA anti-tissue transglutaminase showed a sensitivity of 85% (23/27 coeliac disease cases seropositive), specificity 97% (2/65 controls and one blood donor showing low titre positivity), and a positive predictive value of 92%. High titre anti-tissue transglutaminase was only seen in coeliac disease. Disease controls with mucosal damage unrelated to gluten enteropathy were IgA anti-tissue transglutaminase negative. Sensitivity, specificity, and positive predictive values for IgA anti-endomysial antibody (monkey oesophagus) were 100%, 100%, and 100%, respectively, and for IgA anti-gliadin, 93%, 95%, and 89%, respectively.

CONCLUSIONS

Tissue transglutaminase is a major autoantigen in coeliac disease. IgA (but not IgG) anti-tissue transglutaminase, especially when in high titre, is closely associated with coeliac disease, but low titres may not be disease specific. In this small pilot study, the established IgA anti-endomysial assay was the superior test.

Bone density and bone metabolism are normal after long-term gluten-free diet in young celiac patients

OBJECTIVES

Osteoporosis and alterations of bone metabolism are frequent complications of celiac disease. We evaluated the impact of long-term gluten-free diet (GFD) initiated during childhood and adolescence on bone mineralization and bone metabolism.

METHODS

We studied 30 celiac patients on GFD for > or = 5 yr. The mean age at diagnosis was 11.4+/-5.0 yr, and the mean duration of GFD was 10.7+/-4.3 yr. Results were compared with those obtained in 240 healthy controls. Bone mineral density (BMD) was measured in the lumbar spine and in the whole skeleton by dual-energy x-ray absorptiometry. Serum levels of bone-specific alkaline phosphatase (BALP) and N-terminal propeptide of type I procollagen (PINP) were measured as bone formation indices, and urine levels of N-telopeptide of type I collagen (NTx) as bone resorption index.

RESULTS

BMD measurements of celiac patients (lumbar spine: 1.131+/-0.121 g/cm2; total body: 1.145+/-0.184 g/cm2) did not differ from those of control subjects (lumbar spine: 1.131+/-0.184 g/cm2; total body: 1.159+/-0.118 g/cm2). The levels of BALP, PINP, and NTx of celiac patients did not differ from those of controls. Patients who started GFD before puberty had BMD and bone metabolism measurements comparable to those of patients who started GFD during puberty.

CONCLUSIONS

Our data show that long-term dietary treatment ensures normal mineralization and bone turnover.

Immunological diagnosis of childhood coeliac disease: comparison between antigliadin, antireticulin and antiendomysial antibodies

The immunological markers proposed to supplement intestinal biopsy for the diagnosis of coeliac disease are antigliadin, antireticulin and antiendomysial antibodies. These antibodies have been studied separately or compared as pairs, but no prospective comparison of all three antibodies in childhood coeliac disease exists. Thirty-four confirmed coeliacs were compared with nine non-coeliacs with pathological small intestines, and 32 children with a normal intestinal histology. Sera were examined for IgG- and IgA-antigliadin antibodies (AGA) by ELISA, and for IgA-antireticulin antibodies (ARA) and IgA endomysial antibodies (EMA) by indirect immunofluorescence. In active coeliac disease, IgA-EMA was the most sensitive (97%), while IgA-AGA the least sensitive antibody (52%). The specificity of IgA-AGA, IgG-AGA, IgA-ARA, IgA-EMA was 95%, 92%, 100% and 98%, respectively. Positive predicted values of ARA and EMA were comparable (97-100%), while EMA had the highest negative predicted value (98%). Compared with IgG-AGA, IgA-EMA titres better reflected variations in dietary gluten, and correlated best with intestinal pathology. Compared with AGA and ARA sensitivity, specificity and predictive values, EMA is the most reliable serological marker for the diagnosis of coeliac disease. It reflects dietary changes in gluten and correlates best with intestinal histopathology. Therefore, it should be considered the best of the three serological tests available for childhood coeliac disease.

Endomysial antibody: is it the best screening test for coeliac disease?

The sensitivities and specificities of the IgA and IgG antigliadin antibody and the IgA antireticulin antibody have been compared with the recently described endomysial antibody directed against the basement membrane of smooth muscle in monkey oesophagus. One hundred and seventeen patients with adult coeliac disease (21 untreated), 84 patients with inflammatory bowel disease, systemic lupus erythematosus and rheumatoid arthritis (comprising the disease control group), 47 normal controls and a miscellaneous group of 29 patients, who were selected because of a positive reticulin staining pattern, were investigated. These results were correlated with the degree of abnormality of the intestinal mucosa in patients with adult coeliac disease. Endomysial antibodies were found in all patients with untreated coeliac disease and subtotal villous atrophy and in 47% of patients on a non-strict gluten free diet. One patient on a strict gluten free diet was positive and had partial villous atrophy while all patients in disease control groups were negative. Results were variable with the antireticulin and antigliadin antibodies. Sensitivity and correlation with subtotal villous atrophy in the untreated patients was 100%. It is concluded that the endomysial antibody is superior to other current antibody tests and should be used in preference for the diagnosis of coeliac disease.

Do IgA antigliadin and IgA antiendomysium antibodies show there is latent coeliac disease in primary IgA nephropathy?

The finding in primary IgA nephropathy of increased levels of IgA to food antigens and particularly to gliadin prompted the hypothesis that a subgroup of these patients may have latent coeliac disease. The observation that gliadin may experimentally induce IgA mesangial deposits supported this hypothesis. We evaluated specific immunological markers of coeliac disease (antiendomysium antibodies) which parallel histological changes of gluten sensitive enteropathy, and an IgA immunofluorescent test for antigliadin antibodies in 18 patients with IgA nephropathy, in 56 untreated coeliac disease patients, in 254 controls (58 healthy and 196 disease controls). Antiendomysium antibodies were positive in 89.28% of coeliac patients, but negative in all IgA nephropathies and controls. IgA immunofluorescent test for antigliadin antibodies, negative in all IgA nephropathy patients, was positive in 76.78% of coeliac patients and in 4.91% of controls. ELISA IgA antigliadin antibodies were negative in controls, but positive in 22.22% of IgA nephropathy patients and in 60.71% of coeliac patients. Our data would suggest that in most patients with IgA nephropathy there is no evidence of latent coeliac disease.

Predictive value for coeliac disease of antibodies to gliadin, endomysium, and jejunum in patients attending for jejunal biopsy

OBJECTIVE

To investigate the extent to which the detection of antibodies to gliadin, endomysium, and jejunum predicts the eventual diagnosis of coeliac disease according to the revised ESPGAN diagnostic criteria in a group of patients in whom there is a high suspicion of coeliac disease.

DESIGN

Clinical assessment and laboratory analysis of patients with suspected coeliac disease.

SETTING

Gastroenterology department of teaching hospital.

PATIENTS

96 adults with suspected coeliac disease attending for jejunal biopsy.

MAIN OUTCOME MEASURES

Diagnosis of coeliac disease with the revised criteria of the European Society of Paediatric Gastroenterology and Nutrition in patients with and without antibodies associated with coeliac disease.

RESULTS

28 patients had a clinical diagnosis of coeliac disease, seven of other gastrointestinal diseases, and 12 of miscellaneous diseases; 49 had no diagnosis. Gliadin IgA detected by ELISA was found in all patients with coeliac disease and none of those without, giving a sensitivity, specificity, positive and negative predictive values, and predictive efficiency of 100% for diagnosing coeliac disease within the group. Endomysial IgA was found in 25 (89%) patients with coeliac disease and jejunal IgA in 21 (75%); neither IgA was found in patients without coeliac disease.

CONCLUSION

Detection of gliadin IgA by ELISA and to a lesser extent the endomysial IgA should allow better selection of patients for jejunal biopsy and thus make diagnosing coeliac disease simpler and more efficient.

IgA antiendomysial antibody test. A step forward in celiac disease screening

Serum IgA antiendomysial antibodies (EmA) were found in 61 (87%) of 70 adults and children with untreated celiac disease, whereas IgA antigliadin antibodies (AGA) and IgA R1-antireticulin antibodies (R1-ARA) were positive in 71% and 47%, respectively, of the same patients. Two of the nine untreated celiacs negative for IgA EmA showed positivity for IgA AGA. While IgA AGA and R1-ARA disappeared in all the celiacs tested one year after gluten-free diet, IgA EmA persisted at low titer in seven (18%) of these 38 subjects, although the jejunal biopsy showed a complete regrowth of jejunal villi. All the disease control patients as well as the blood donors tested were always negative for the three IgA antibodies. Our results state that the search for both IgA EmA and AGA gives the best results in the screening of celiac disease, since the positivity for at least one of these two antibodies allows identification with a 100% specificity of the 90% of untreated celiac patients.

Gluten-sensitive enteropathy in childhood

Genetic and environmental factors (breast feeding, probably viral infections) play a role in the expression of the disease. Prevalence of GSE in childhood did not substantially decrease in the last 15 years in all European countries, where GSE is still more common in infantile age and presents frequently gastrointestinal symptoms. A decrease has been reported in childhood in several United Kingdom areas and in Finland, where the clinical presentation is changing, shifting upward with age and coming closer to the adult type of the disease. The following clinical problems have been reported in the recent literature: enamel hypoplasia; monosymptomatic short stature; arthritis and other immunologic diseases; association with diabetes, atopy, Iga deficiency, and probably Down's syndrome. Delay in puberty and other peculiar problems of the disease have been described in adolescents. Tests assessing the permeability of the small intestine and the blood levels of antigliadin antibodies have recently gained success as noninvasive tools for the diagnosis of the GSE. The gluten should be withdrawn from the diet and the challenge with gluten should be performed not before 12 months of gluten-free diet with an accurate timing of the biopsy on the basis of the antigliadin and antireticulin antibodies, to avoid clinical and growth damage. Celiac children do require a permanent gluten-free (and not poor) diet. In reality, too many celiac adolescents are off-diet.

Antibodies to dietary antigens in coeliac disease

Antibodies to gliadin (AGA) were found in 77 (94%) of 82 sera from patients with active coeliac disease (untreated and after gluten challenge). Although IgG AGA had a higher nosological sensitivity than IgA AGA (88% versus 67%), their nosological specificity was lower than that of IgA antibodies (87% versus 100%). The sensitivity of antibodies to casein, beta-lactoglobulin, and ovalbumin in active coeliac disease varied from 36% to 48% without significant difference between IgG and IgA antibodies. IgG and IgA antibodies to milk and egg proteins showed a specificity similar to that of AGA, although some IgA antibodies other than AGA were found in disease controls (Crohn's disease, ulcerative colitis, post-enteritis syndrome).

Anti-reticulin antibodies: a diagnostic and monitoring test for childhood coeliac disease

The importance of anti-reticulin antibodies (ARA)--R1 pattern--has been evaluated as a diagnostic and monitoring test for childhood coeliac disease. A prospective study was performed in 140 patients: 68 children with coeliac disease, 32 with miscellaneous diarrhoea, and 40 controls. An indirect immunofluorescent test was used for ARA screening. The indirect correlation found in our study between the presence of ARA and coeliac disease in children on a normal diet and after gluten challenge and between the absence of ARA and coeliac disease in children on a gluten-free diet seems to be of value in the diagnosis of coeliac disease and in monitoring the response to treatment in coeliac disease children.

Gliadin antibody detection in gluten enteropathy

Circulating antigliadin antibody has been described in patients with gluten enteropathy although the prevalence varies in different studies. It has been suggested that the investigation for antigliadin antibody might be useful as a screening test. The object of the present study was to evaluate two different techniques for assaying these antibodies - an indirect immunofluorescent method and an enzyme-linked immunosorbent assay (ELISA). Antibodies were assayed in the sera of 102 patients in whom jejunal biopsies were also obtained. The specificity of both tests was greater than 95%, and the correlation between the presence of antibody and histology was significant (p < 0.005), though the sensitivity of each test was less than 70%.

Serum IgG subclass antibodies to gliadin and other dietary antigens in children with coeliac disease

IgG subclasses of antibodies to the dietary antigens gliadin, glycgli (a gluten component), ovalbumin (OA) and beta-lactoglobulin (BLG) were quantified in children with coeliac disease (CD), nine on a gluten-containing diet, 15 on a gluten-free diet, and in appropriate controls. In addition, total serum IgG subclasses were measured. IgG1 and IgG3 antibodies to gluten and glycgli were detected in 9/9 and 8/9 CD-patient on a gluten-containing diet, respectively, and in 4/15 and 6/15 patients on a gluten-free diet. None of the controls had appreciable levels of IgG1 antibodies and only 1/22 of the controls had IgG3 antibodies to gliadin and glycgli. IgG2 and IgG4 antibodies to the same antigens were found in a few coeliacs and controls. Consecutive samples from coeliac children (8 patients) showed a clear relation between the exposure to gluten and a rise in IgG1 (8/8) and IgG3 antibody levels (7/8). In contrast, IgG antibodies to OA and BLG were almost exclusively of the IgG1 and IgG4 subclasses. The highest levels were found in children with CD, but the differences between the groups were not significant. Total serum IgG subclasses did not differ between the groups, but the IgG2 and IgG4 levels in most coeliac children were low. The production of IgG1 and IgG3 antibodies to gluten components may be an important precondition for the development of coeliac disease in susceptible individuals.

Serum antibodies to gliadin and small-intestinal morphology in dermatitis herpetiformis. A controlled clinical study of the effect of treatment with a gluten-free diet

Serum gliadin antibodies of the IgA and IgG classes were determined by the diffusion-in-gel enzyme-linked immunosorbent assay in 41 patients with dermatitis herpetiformis before treatment with a gluten-free diet. Increased gliadin antibody levels were found more frequently in patients with subtotal villous atrophy (9 out of 17 patients, or 53%; p less than 0.05) than in patients with partial villous atrophy (2 out of 13 patients, or 15%) or normal villous appearance (2 out of 10 patients, or 20%). The gliadin antibody levels were negatively correlated with the urinary xylose excretion (r = -0.40, p less than 0.02 for the IgA class and r = -0.64, p less than 0.001 for the IgG class). Intestinal morphology improved and mean gliadin antibody levels of the IgA and IgG classes decreased during treatment with a gluten-free diet for 16-36 months (mean, 20 months) (p less than 0.005, n = 26), whereas no significant changes of the gliadin antibody levels or the small-intestinal morphology were observed in the other 15 patients, who continued on a non-restricted diet for 17-35 months (mean, 20 months). Thus, gliadin antibody levels in sera from patients with dermatitis herpetiformis seem to be correlated with the severity of the intestinal disease. However, all patients with villous atrophy are not detected by determination of serum gliadin antibodies.

Arthritis and coeliac disease

We report six patients with coeliac disease in whom arthritis was prominent at diagnosis and who improved with dietary therapy. Joint pain preceded diagnosis by up to three years in five patients and 15 years in one patient. Joints most commonly involved were lumbar spine, hips, and knees (four cases). In three cases there were no bowel symptoms. All were seronegative. X-rays were abnormal in two cases. HLA-type A1, B8, DR3 was present in five and B27 in two patients. Circulating immune complexes showed no consistent pattern before or after treatment. Coeliac disease was diagnosed in all patients by jejunal biopsy, and joint symptoms in all responded to a gluten-free diet. Gluten challenge (for up to three weeks) failed to provoke arthritis in three patients tested. In a separate study of 160 treated coeliac patients attending regular follow up no arthritis attributable to coeliac disease and no ankylosing spondylitis was identified, though in a control group of 100 patients with Crohn's disease the expected incidence of seronegative polyarthritis (23%) and ankylosing spondylitis (5%) was found (p less than 0.01). Arthritis appears to be a rare manifestation of coeliac disease. This relationship may provide important clues to the role of gastrointestinal antigens in rheumatic diseases.

Antibodies to gliadin detected by immunofluorescence and a micro-ELISA method: markers of active childhood and adult coeliac disease

Antibodies to gliadin have been detected by immunofluorescence (IFL-AGA) and a micro-ELISA method (ELISA-AGA) in 45 out of 47 (96%) sera from patients with active childhood and adult coeliac disease. The two methods were more sensitive than R1-reticulin antibodies (R1-ARA) which were found only in 28 of the same patients (60%). R1-ARA were always negative in the 26 sera from patients with childhood coeliac disease and adult coeliac disease after gluten free diet, while IFL- and ELISA-AGA were respectively found in three (12%) and in four (15%) out of these patients. Moreover, while R1-ARA and IFL-AGA were strictly confined to coeliac disease. ELISA-AGA were occasionally found in patients with control diseases. These 'false positive' antibodies were all of IgG class and had low titres. In our experience IFL- and ELISA-AGA of IgA class were strictly confined to active childhood coeliac disease and adult coeliac disease. The detection of AGA is useful in monitoring the diet and in the follow up of coeliac disease. IFL- and ELISA-AGA, then, are to be preferred to R1-ARA for the screening of coeliac patients.

Can antigliadin antibody detect symptomless coeliac disease in children with short stature?

Duodenal biopsy and tests for antigliadin antibodies were done in 108 children with short stature unassociated with gastrointestinal symptoms. Other investigations for causes of growth failure were also carried out. In 88 patients, the cause of short stature could not be determined (group I). In 9 patients (8.3%) biopsy showed total villous atrophy, indicating probable coeliac disease (group II), while 7 patients had mild partial villous atrophy (group III). 4 patients (3.7%) had complete growth hormone deficiency. Antigliadin antibodies detected by immunofluorescence (IFL-AGA) were positive in 8 of the 9 group II patients. Symptomless coeliac disease is therefore a commoner cause of short stature than is hypopituitarism; by use of the IFL-AGA test it is possible to select patients for biopsy, thereby identifying most of the coeliac patients. If duodenal biopsies had been limited to IFL-AGA positive patients, 18 biopsies would have been carried out and coeliac disease would have been diagnosed in 8 of the 9 patients.

Specific IgG subclass antibodies, IgE and IgG S-TS antibodies to wheat gluten fraction B in patients with coeliac disease

Antibodies were measured in the sera of fifteen patients with untreated coeliac disease and twenty-eight patients with inflammatory bowel disease. Increased levels of specific IgG, IgG1, IgG2, and IgG4 antibody to wheat gluten fraction B, measured by an enzyme-linked immunosorbent assay, were shown in the coeliac disease group, but not in the inflammatory bowel disease group. No specific IgE antibody to fraction B was detected but 33% of the patients with coeliac disease had specific short-term sensitizing (anaphylactic) IgG antibody activity (IgG S-TS) to fraction B. There was no correlation between the IgG2 or IgG4 specific antibody and the presence of IgG S-TS activity.

Evaluation of a serum IgA-class reticulin antibody test for the detection of childhood celiac disease

Serum IgA class reticulin antibody (RA) was found in 28 (97%) of 29 children with flat small bowel mucosa, and in low titer in four (2%) of 245 with normal or near normal mucosa on small intestinal biopsy. Thus the sensitivity of the IgA-RA fluorescent antibody test for screening of celiac disease was 97% and the specificity 98%. IgA-RA was superior to IgG-RA for the detection of celiac disease. During follow-up of patients receiving a gluten-free diet, the IgA-RA rapidly decreased and in most cases disappeared within a year, suggesting that the test may be useful for clinical follow-up of celiac disease as well.

Serum gliadin antibodies for detection and control of childhood coeliac disease

Serum gliadin antibodies of the IgA and IgG isotypes were determined by means of the diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) in children during different phases of coeliac disease. Fourteen children were studied before onset of dietary treatment, 16 during a period of gluten-free diet and 16 during gluten challenge. The control groups consisted of 44 children with other gastrointestinal diseases and 14 children without gastrointestinal disorders. All of the children studied had been subjected to small-intestinal biopsy. On the basis of the results obtained in this study the diagnostic sensitivity with regard to untreated coeliac disease was found to be 100% and the diagnostic specificity 97%. In 10 coeliac children followed during the phases of diagnostic evaluation antibody levels decreased in all during dietary treatment and increased in 8 during a subsequent gluten challenge. It is suggested that determination of IgA and IgG gliadin antibodies by means of DIG-ELISA may be used as a diagnostic test for coeliac disease in children and that this test may be useful in monitoring the dietary treatment in children with known coeliac disease. Moreover, the DIG-ELISA is an inexpensive and technically simple method.

Antibodies to gliadin, gluten and reticulin glycoprotein in rheumatic diseases: elevated levels in Sjögren's syndrome

An enzyme immunoassay was used to measure circulating antibodies to gluten, gliadin and to 'reticulin glycoprotein' in 25 patients with Sjögren's syndrome (SS), in 20 patients with rheumatoid arthritis without SS and in 19 patients with systemic lupus erythematosus without SS. Antibody levels to these three antigens were significantly higher in SS than in the other groups. In SS the level of antibodies to 'reticulin glycoprotein' correlated positively with the levels of antibodies to both gliadin and to gluten but not with the level of antibodies to SS-B antigen. Patients with primary SS had higher antibody levels to 'reticulin glycoprotein' than had patients with secondary SS, whereas no significant difference between primary and secondary SS was found in the levels of the antibodies to gliadin or to gluten. Circulating antibodies to gliadin, gluten and 'reticulin glycoprotein' have not been previously recognized in SS. Their occurrence suggests that small bowel injury may be a common finding in SS.

Down's syndrome: nutritional intervention

Down's Syndrome patients are known to be of short stature, prone to infections, autoimmune disease, hypothyroidism, leukaemia, heart defects and later Alzheimer's disease. They tend to have older mothers, like Alzheimer's disease patients. The latter tend to have sibs with either Down's Syndrome or lymphoma/leukaemia. Evidence, looking at 28 Down's Syndrome patients, suggests that multiple food allergies, gluten-gliadin sensitivity or intolerance are causing a coeliac disease-like picture with a malabsorption state for essential vitamins, minerals and severe autoimmune disease. It is hoped that missed gluten-gliadin sensitivity or intolerance with or without coeliac disease will be considered as a cause of abnormal oogenesis and spermatogenesis resulting in trisomy 21 and other aneuploidies. The mechanism most likely is low B1 interfering with sufficient release of cAMP for normal meiosis. Alternatively exorphins and peptides from foods may suppress prostaglandin E1 synthesis, or food sensitivities may alter toxic metal absorption mechanisms, which are thought to play a role in the development of Alzheimer's disease. Adequate vitamin/mineral supplementation, especially B1, prior to conception and in the first trimester is recommended for mothers at risk for DS, especially older mothers and a gluten free diet for those with coeliac disease or gluten-gliadin sensitivity/intolerance. Hopefully this will prevent conception of a DS child, or prevent heart defects/stigmata if one is conceived. DS children should be investigated for the above and commence a food allergy free diet with relevant supplements to meet their needs as early as maximum development.

A solid-phase radioimmunoassay for IgG gliadin antibodies using 125I-labelled staphylococcal protein A

A sensitive radioimmunoassay for IgG gliadin antibodies is described. Serum specimens were added to wells of plastic microtitre plates coated with gliadin. After removal of the unbound material, gliadin antibodies were detected by adding 125I-labelled staphylococcal protein A (125I-SpA). Serum specimens from coeliac patients on a normal diet or on a gluten-free diet were tested, as well as sera from an age-matched control group. Measurements to obtain precise quantitative values were made with gliadin antibody-rich serum as reference standard. High titres of gliadin antibodies were found in 18 out of 19 coeliac patients on a normal diet (95%); in patients on a strict gluten-free diet serum values did not exceed 2 S.D. of the control mean. Due to the high sensitivity of the method a low but detectable amount of gliadin antibody was present in the sera of all controls.

A solid-phase radioimmunoassay for measurement of circulating antibody titres to wheat gliadin and its subfractions in patients with adult coeliac disease

A solid-phase radioimmunoassay for the measurement of circulating antibody titres to wheat gliadin is described. Using this assay, we have measured antibody titres to unfractionated gliadin in normal healthy controls, in coeliac patients on a gluten-free or a normal diet, and in patients with ulcerative colitis and Crohn's disease. High titres of antibodies to unfractionated gliadin were observed only in the patients with untreated coeliac disease. Antibody titres to alpha, beta, gamma and omega gliadin subfractions were measured in patients with untreated coeliac disease and compared with titres in normal controls. Patients with untreated coeliac disease had higher antibody titres to the gliadin subfractions. No specific pattern of circulating antibody titres to gliadin subfractions was observed in the untreated coeliac patients which would provide a diagnostic profile. These results suggest shared antigenicity between the gliadin subfractions.

Gluten-sensitive enteropathy. Immunoglobulin G heavy-chain (Gm) allotypes and the immune response to wheat gliadin

Anti-gliadin antibody was measured by radioimmunoassay in 30 Caucasians with gluten-sensitive enteropathy (GSE). 22 GSE patients maintained on a gluten-free diet for 1.5 to 20 yr (mean duration 76 mo) had elevated serum concentrations of IgG antigliadin antibody. Among GSE patients on a gluten-free diet, antigliadin antibody was seen only in those having the chromosome 14-encoded IgG immunoglobulin heavy chain allotype marker G2m(n). IgG antigliadin antibody was found in GSE patients with G2m(n) regardless of whether the HLA-B8 and/or -DR3 major histocompatibility complex antigens that occur frequently in GSE were present. No patient lacking G2m(n) had significant levels of antigliadin antibody. The association between antigliadin antibody and the immunoglobulin heavy chain allotype marker G2m(n) in GSE patients likely reflects the presence of Gmn-linked variable region genes or Gmn-linked genes that regulate variable region gene expression.

IgA antigliadin antibodies: a marker of mucosal damage in childhood coeliac disease

Antigliadin antibodies in serum samples of 31 children with coeliac disease were measured by an enzyme-linked immunosorbent technique. In young patients (less than 2 years) tested before gluten withdrawal IgA antigliadin antibody levels were invariably above the levels of 36 controls. The titres fell rapidly when gluten was eliminated from the diet and rose on its reintroduction. The titres were not always greater than the control level in older untreated patients. IgA antigliadin antibodies seem to be a good marker of the immune reaction in the jejunum triggered by gluten. In 2 IgA-deficient patients gluten challenge caused an increase in IgM antigliadin antibodies, and at the same time the number of IgM-containing cells increased in the jejunal mucosa. Rising IgG antigliadin antibody levels after gluten elimination were seen in 6 patients, 5 of whom had very low complement C3 levels before gluten elimination.

Linear IgA disease in adults

A multi-centre study is described in which thirty-five adult patients with papillary IgA dermatitis herpetiformis (DH) were compared with forty-two patients with linear IgA deposits, of whom thirty-four had homogeneous-linear (HL) and eight had granular-linear (GL) IgA deposits. The three groups were similar with regard to age of onset, presence of circulating immune complexes and auto-antibodies, incidence of spontaneous remission, histology of lesional skin and response to dapsone. There was a female predominance in the HL group in contrast to the male predominance in the other two. It was not possible to diagnose the HL group clinically. Some patients had a rash typical of DH whilst others resembled pemphigoid. In the majority, however, no specific diagnosis could be made with confidence. The GL group clinically resembled the DH group. The incidence of positive potassium iodide patch tests was greater in the DH group than in the other two. An associated enteropathy was found in 24% of patients in the HL group, 30% of patients in the GL group and 85% of patients in the DH group. Fifty-six percent of HL patients had HLA-B8 compared with 50% in the GL group and 88% in the DH group. Patients with linear IgA deposits may not be a uniform group, but until they can be divided into specific subgroups (e.g. by ultrastructural localization of the deposit or by response to a gluten-free diet) we propose that the term adult linear IgA diseases should be used to distinguish these patients from those with papillary IgA deposits.

Anti-gliadin antibodies and small intestinal mucosal damage in dermatitis herpetiformis

Sera from forty-six patients with dermatitis herpetiformis (DH) were examined for anti-gliadin antibodies (AGA) by the enzyme linked immunosorbent assay (ELISA) test and by a simple new immunofluorescent (IF) test. AGA were present in fifteen out of thirty-two patients taking a normal diet, but in none of the fourteen taking a gluten-free diet (GFD). The presence of circulating AGA was related to the severity of the enteropathy. AGA were present in all ten patients with a flat mucosa and in four of six with a convoluted mucosa, but in only one out of thirty patients with normal morphology of the small intestine. However, in those patients taking a normal diet and with a normal morphology of the intestine there was evidence of gluten sensitivity compared to those taking a GFD, as the intraepithelial lymphocyte count (IELC) was significantly raised in the peri-nuclear and supra-nuclear positions. The study shows that the presence of AGA in the serum is a good indication of the degree of gluten sensitivity as expressed by severe mucosal damage in patients with DH.