Celiac disease

Increased Mercury Levels in Patients with Celiac Disease following a Gluten-Free Regimen

Background and Aim. Although mercury is involved in several immunological diseases, nothing is known about its implication in celiac disease. Our aim was to evaluate blood and urinary levels of mercury in celiac patients. Methods. We prospectively enrolled 30 celiac patients (20 treated with normal duodenal mucosa and 10 untreated with duodenal atrophy) and 20 healthy controls from the same geographic area. Blood and urinary mercury concentrations were measured by means of flow injection inductively coupled plasma mass spectrometry. Enrolled patients underwent dental chart for amalgam fillings and completed a food-frequency questionnaire to evaluate diet and fish intake. Results. Mercury blood/urinary levels were 2.4 ± 2.3/1.0 ± 1.4, 10.2 ± 6.7/2.2 ± 3.0 and 3.7 ± 2.7/1.3 ± 1.2 in untreated CD, treated CD, and healthy controls, respectively. Resulting mercury levels were significantly higher in celiac patients following a gluten-free diet. No differences were found regarding fish intake and number of amalgam fillings. No demographic or clinical data were significantly associated with mercury levels in biologic samples. Conclusion. Data demonstrate a fourfold increase of mercury blood levels in celiac patients following a gluten-free diet. Further studies are needed to clarify its role in celiac mechanism.

Development of a Monoclonal Antibody Capable of Detecting Prolamine in Wheat and Oats

A monoclonal antibody (MAb) capable of detecting the gliadin in wheat flour has been developed. By immunoblot, the monoclonal antibody recognized three bands in the membranes after electrophoresis in an SDS PAGE of the alcohol-soluble proteins of wheat, and only one band in the alcohol extract of the oat flour. ELISA technique can be applied using this monoclonal antibody in the detection of gliadin and avenin in samples from wheat or triticale. The characterization of the antibody shows that it is an IgM class. Sensitivity by ELISA to the gliadin was 80 ng/ml.

Coeliac disease in Sjögren's syndrome--a study of 111 Hungarian patients

Recent studies report that in patients with Sjögren's syndrome (SS), concomitant coeliac disease (CD) is more frequent than in the average healthy population, with dominance of the latent/silent form. We further investigated this to characterise the clinical and immunolaboratory features of SS patients with CD. One hundred and eleven patients with SS were involved in the study. After detailed history, blood samples were taken for antibodies to gliadin, endomysium, and tissue transglutaminase. Of them, six had positive serology for CD and underwent jejunoscopy and small bowel biopsy to confirm the diagnosis of CD. In five patients, the diagnosis was established histologically. The frequency of CD in the SS population was significantly higher than in the non-SS European population (4.5:100 vs 4.5-5.5:1,000). Laboratory findings in these patients showed significantly higher erythrocyte sedimentation rates and IgG, IgA, and IgM levels. On the basis of these findings, we recommend screening, follow-up, and regular gastrointestinal care of SS patients to identify CD cases and help them to avoid severe malnutrition and intestinal malignancies.

Transition of care between paediatric and adult gastroenterology. Coeliac disease

Coeliac disease is a condition in which there is an abnormal mucosa in the small intestine. It improves with a gluten free diet, with avoidance of wheat, rye, barley and possibly oats. The history and epidemiology of this condition are discussed. Diagnosis is based on demonstrating that the characteristic histological abnormalities in the small intestine are dependent on gluten ingestion. Diagnostic pitfalls are discussed. The anti-endomysium and anti-tissue transglutaminase antibodies are specific and sensitive diagnostic tools. The wide variety of clinical symptoms and presentations are discussed including the associated condition of dermatitis herpetiformis. Failure to respond to a gluten-free diet can represent simple dietary problems, an alternative diagnosis or, occasionally, the development of a serious complication of coeliac disease such as ulcerative jejunitis or enteropathy-associated T cell lymphoma. Progress towards the characterization of the toxic epitopes within gluten that exacerbate coeliac disease and our current understanding of the genetics of the disorder are presented.

Coeliac disease and reproductive disorders: a neglected association

Coeliac disease is a chronic disease caused by a permanent intolerance to ingested gluten resulting in immunologically mediated inflammatory damage of the small-intestinal mucosa. The wide spectrum of clinical symptoms is partly due to the malnourished state caused by the malabsorption of macro- and micronutrients. Fertility problems, sexual dysfunction and obstetrical complications are more frequently observed in patients with coeliac disease. These reproductive disorders may be a consequence of the endocrine derangements caused by selective nutrient deficiencies. Nowadays, the early diagnosis and treatment of coeliac disease is possible and not very costly. Therefore, coeliac disease must be seriously considered in the preconceptional screening and treatment of patients with reproductive disorders.

Synergistic effect of two HLA heterodimers in the susceptibility to celiac disease in Tunisia

The DR and DQ HLA genotypes of 94 Tunisian children affected with celiac disease are analyzed so that we can gain a better understanding of the HLA component of this disease. All of them carry at least one of two specific heterodimers: a DQ heterodimer, encoded by DQA1*0501, DQB1*0201 and/or a DR heterodimer, encoded by the nonpolymorphic gene DRA and the DRB4 gene. Quantifying the relative penetrances of all susceptible genotypes gives evidence for a synergistic effect of these two heterodimers and for a dose effect of the alleles encoding the beta chains of these two heterodimers. The DR3DR7 individuals have the greatest risk. They present the two kinds of heterodimers and carry two DQB1*0201 alleles. Celiac disease is the first HLA-associated disease for which the at-risk genotypes are so well delineated.

Colonic histopathology in untreated celiac sprue or refractory sprue: is it lymphocytic colitis or colonic lymphocytosis?

Colonic histopathology in some patients with untreated celiac sprue and refractory sprue has been said to be indistinguishable from lymphocytic colitis, but there have been no objective comparisons on which this is based. The purpose of this study was to determine the prevalence and to characterize the nature of colonic histopathology at the time of diagnosis in patients with celiac or refractory sprue. Colonoscopic biopsy specimens obtained at the time of diagnosis from 16 patients with celiac sprue, six patients with refractory sprue, nine patients with lymphocytic colitis, and five normal controls were analyzed blindly by histological and morphometric methods, quantitating the number and specific subtypes of inflammatory cells within the lamina propria and epithelium. Immunoperoxidase staining of intraepithelial lymphocytes with a monoclonal antibody to CD8 also was performed. Three of 16 patients with untreated celiac sprue (19%) were thought to have colonic histological abnormalities, which by morphometry consisted of slightly increased numbers of lymphocytes in the surface epithelium and lamina propria, many of which were CD8-positive. These abnormalities were distinguishable from lymphocytic colitis by the lack of increased overall lamina propria cellularity and surface epithelial abnormalities, and by fewer intraepithelial lymphocytes. In refractory sprue, colonic histological abnormalities were more frequent than in celiac sprue, occurring in four of six patients (67%), more pronounced, and identical to those in the lymphocytic colitis syndrome. However, colonic intraepithelial lymphocytes in lymphocytic colitis were mostly CD8-positive, whereas those in the colitis of refractory sprue rarely were. Mild colonic lymphocytosis in patients with untreated celiac sprue should be distinguished from lymphocytic colitis by the lack of surface epithelial abnormalities, the lack of increased cellularity of the lamina propria, and the lack of ongoing watery diarrhea after treatment with a gluten-free diet. In contrast, colonic histopathology in refractory sprue is indistinguishable from lymphocytic colitis, although immunohistochemical differences do exist.

Antigliadin antibody measurement by chemiluminescence ELISA in the diagnosis of coeliac disease

AIMS

To develop a chemiluminescence enzyme linked immunosorbent assay (ELISA) for the detection of circulating gliadin antibodies in the diagnosis of coeliac disease. To compare this method for linearity and sensitivity with an established colorimetric method.

METHODS

Three sets of age and sex matched patient groups were studied: normal controls (patients with no clinical signs of intestinal disorders); gastrointestinal controls (patients with a known gastrointestinal disorder other than coeliac disease); and patients in whom suspected coeliac disease had been confirmed by positive jejunal biopsy. IgG antigliadin antibody (IgG-AGA) and IgA antigliadin antibody (IgA-AGA) titres were determined.

RESULTS

Comparison of the colorimetric and chemiluminescence methods showed close correlation of measured antibody levels for both control patient groups. In the coeliac patients correlation of antibody levels measured by both methods was not possible because the colorimetric assay is limited by the spectrophotometer's limits of detection. This problem was overcome by the chemiluminescence method which was linear over a greater range and to far higher values.

CONCLUSIONS

The chemiluminescence ELISA performs as well as the colorimetric assay at low and average antibody levels and has the advantage of also giving a numerical value to higher antibody titres. The method was accurate and reproducible in confirming the diagnosis of coeliac disease in patients with positive jejunal biopsy and was capable of monitoring progress of the disease.

Immunological analysis of serum for buckwheat fed celiac patients

Buckwheat (Fagopyrum esculentum, Moench), a herbaceous plant of the Polygonaceae family, does not have any affinity for the Gramineae family. It is commercially rated as a cereal, which has led to some misunderstanding concerning its use in gluten induced enteropathy or celiac disease. The effect of buckwheat flour ingestion by celiac patients was evaluated through the indirect immunofluorescence technique. Samples of serum were collected 30 days after the flour ingestion. Cryostat performed cuts of wheat and buckwheat grains were accomplished in order to compare the reactivity of their proteins and serum of celiac and normal patients. The assay revealed that the buckwheat flour presents no toxicity for the celiac patient and no anti-protein antibodies formation in the grain was observed for serum dilutions of 1:2 up to 1:32 with 0.15 M NaCl solution in 0.01 M phosphate buffer, pH 7.2 throughout the 30 day assay period. The results of the immunological assays showed that the buckwheat flour does not present toxic prolamines to celiac disease patients.

Unsuspected coeliac disease in chronic 'cryptogenic' liver disease

BACKGROUND

Earlier reports have suggested that a relationship exists between chronic liver disease and coeliac disease (CD). Gliadin antibodies (GA) have been used to screen for CD.

METHODS

Using a micro-enzyme-linked immunosorbent procedure, we analysed sera from 327 consecutive patients with chronic liver disease for GA (IgA and IgG) and evaluated their clinical significance.

RESULTS

GA were detected in 19 patients (6%), a prevalence six times greater than that found in healthy blood donors. In 9 of the 19 patients the liver disease had been classified as cryptogenic. The occurrence of GA was independent of the degree of hepatocellular impairment. A diagnosis of CD was confirmed in 5 of the 10 patients who underwent small-bowel biopsy.

CONCLUSIONS

Our findings suggest the prevalence of CD in patients with chronic liver disease to be at least 1.5%--that is, 15 times higher than in the general population. They also suggest that the possible presence of CD should be considered in cases of chronic 'cryptogenic' liver disease.

HLA susceptibility genes in celiac disease: genetic mapping and role in pathogenesis

The overrepresentation of particular HLA alleles in patients with celiac disease was first noted two decades ago. Several lines of evidence obtained during the last years strongly suggest that a particular HLA-DQ heterodimer, encoded by the DQA1*0501 and DQB1*0201 genes in cis or trans configuration, confers the primary disease susceptibility. This paper reviews the evidence behind this concept and discusses how this particular DQ molecule may be involved in the pathogenesis.

Do adults with high gliadin antibody concentrations have subclinical gluten intolerance?

Gliadin antibodies of the IgG and IgA isotypes and IgG subclasses were measured in 200 adults who were randomly selected from the Icelandic National Register. Those with the highest gliadin antibody concentrations were invited with negative controls to participate in a clinical evaluation. Neither the study subjects nor the physicians who recorded and evaluated the clinical findings were aware of the antibody levels. Significantly higher proportion of the gliadin antibody positive individuals reported unexplained attacks of diarrhoea (p = 0.03), and IgA gliadin antibodies were associated with increased prevalence of chronic fatigue (p = 0.0037). The gliadin antibody positive group also showed significantly decreased transferrin saturation, mean corpuscular volume and mean corpuscular haemoglobin compared with the gliadin antibody negative controls. Serum folic acid concentrations were significantly lower in the IgA gliadin antibody positive individuals. On blind global assessment 15 of the 48 participants were thought to have clinical and laboratory features that are compatible with gluten sensitive enteropathy, and 14 of these were in the gliadin antibody positive group (p = 0.013). Complaints that have not been associated with gluten intolerance had similar prevalence in both groups with the exception of persistent or recurrent headaches that were more common in the gliadin antibody positive group. These findings raise the possibility that a subclinical form of gluten intolerance may be relatively common.

Jejunal secretion of secretory immunoglobulins and gliadin antibodies in celiac disease

The aim of this study was to determine the secretion of secretory immunoglobulins and gliadin antibodies in the small bowel in celiac disease. Twenty-four patients were investigated by perfusion of a defined jejunal segment. Four of the patients studied had a serum IgA deficiency and had no measurable amounts of secretory IgA in the perfusion fluid. The other patients demonstrated a significant increase in the jejunal concentration of secretory IgA (median 28.5 mg/liter) compared with healthy controls (median 16 mg/liter, N = 16) and of IgM, celiac (median 12.3 mg/liter) compared to healthy controls (median 6.8 mg/liter, N = 16). Jejunal IgA gliadin antibodies were detected in all patients except those with an IgA deficiency. All patients had jejunal IgM gliadin antibodies, but none of the patients had measurable jejunal IgG gliadin antibodies. A positive correlation was detected between serum and jejunal IgA gliadin antibody levels in the celiac patients, (P less than 0.01). Calculation of the ratio between gliadin antibodies and total levels of IgA and IgM in serum and jejunal perfusate demonstrated that the jejunal synthesis of gliadin antibodies of IgA and IgM type is both more pronounced and persistent than the systemic humoral immune response to gliadin.

A new distinct group of 2 S albumins from rapeseed. Amino acid sequence of two low molecular weight napins

Two napins (nIa and nIb), isolated from Brassica napus (rapeseed) seeds, have been sequenced. The two proteins show the common structural pattern of the 2 S albumins, since they are composed of two disulfide-linked chains of different size, yet they exhibit an atypical low molecular weight (12.5 kDa vs. 14.5 kDa of the major napins). High sequence similarity has been found between these 2 proteins, but only 54% similarity can be estimated from their comparison with the 14.5 kDa major napins. Thus, nIa and nIb are considered representatives of a new distinct group of rapeseed napins since all the previously known napins exhibit 95% sequence similarity. Unexpectedly, the similarity increases when compared with the 2 S proteins from other species.

Fc receptor function and circulating immune complexes in gluten sensitive enteropathy--possible significance of serum IgA

The capacity to clear IgG containing immune complexes from the circulation was studied in patients with coeliac disease (n = 13), dermatitis herpetiformis (n = 8), and coeliac disease with concomitant serum IgA deficiency (n = 4). A small group of patients with active ulcerative colitis (n = 4) was included as a bowel disease control group. Clearance was estimated by measuring the disappearance rate of a bolus dose of intravenously injected IgG coated autologous erythrocytes. The mean T1/2 of clearance was prolonged in both coeliac disease (86 (24) minutes) and dermatitis herpetiformis (111 (35) minutes), compared with healthy subjects (20 (5) minutes) and coeliac patients with concomitant serum IgA deficiency (T1/2 = 17 (6) minutes). Patients with ulcerative colitis had a prolonged clearance, with a T1/2 of 195 (63) minutes. Values of circulating immune complexes were measured by four assays; C1q binding and C3, IgG, and IgA containing immune complexes. C1q binding immune complexes were detected only in IgA deficient gluten sensitive enteropathy. Patients with coeliac disease and dermatitis herpetiformis had higher values of C3, IgG, and IgA containing immune complexes than control subjects and serum IgA deficient patients with coeliac disease. The clearance rate was inversely correlated to the amount of immune complexes for the subgroups of gluten sensitive enteropathy.

Conformational studies of peptides corresponding to the coeliac-activating regions of wheat alpha-gliadin

The structures of four peptides corresponding to parts of the coeliac-activating protein A-gliadin were studied by structure prediction and c.d. spectroscopy. Three of the peptides corresponded to parts of the coeliac-activating N-terminal region (residues 3-55, 3-19 and 39-45) and contained two tetrapeptide motifs common to all coeliac-active regions (Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro). The Pro-Ser-Gln-Gln sequence was also present in the fourth peptide, on the basis of the C-terminal part of the molecule (211-217). These studies showed that beta-reverse turns were the predominant structural feature in all peptides and were predominantly of type I/III in two of the N-terminal peptides and type II in the C-terminal peptide. These turns form when the peptide is dissolved in solvents of low dielectric constant (trifluoroethanol) and high dielectric constant (water and iso-osmotic saline), although their presence in the N-terminal peptides may be masked in the latter solvents due to equilibrium with a poly-L-proline II structure favoured at lower temperatures.

Gliadin challenge-induced jejunal prostaglandin E2 secretion in celiac disease

Jejunal prostaglandin E2 secretion in patients with adult celiac disease was studied under basal conditions and after local gliadin challenge. A newly developed tube system with occluding balloons was used to perfuse a jejunal segment. After an initial basal perfusion period of 40 minutes, an average of 12 mg +/- 3 (SEM) of crude gliadin was administered into the perfused segment. Perfusion continued for an additional 100 minutes and prostaglandin E2 was determined in the effluent with a radiometric method. Patients with histologically active celiac disease (n = 7) had higher basal jejunal secretion of prostaglandin E2, 523 +/- 229 pg.cm-1.h-1 (mean +/- SEM), than both celiac patients with normalized small bowel mucosa (n = 6), 160 +/- 44 pg.cm-1.h-1, and healthy controls (n = 18), 184 +/- 38 pg.cm-1.h-1, (P less than 0.05). After gliadin challenge of the jejunal segment, a significant increase (P less than 0.05) in prostaglandin E2 secretion was noted in patients with celiac disease (n = 10). The individual maximum increase was on average fivefold and occurred 60-100 minutes after gliadin administration. In healthy controls (n = 5), no alteration in prostaglandin E2 secretion was detected after gliadin challenge. Enhanced jejunal prostaglandin 2 synthesis may be involved in the pathophysiological processes initiated by gliadin in patients with celiac disease.

Antibody response reveal differences in oral tolerance to wheat and maize grain protein fractions

The influence of diet on humoral immune responses to gluten- and maize-derived proteins was examined using ELISA and protein blotting techniques. Mice raised on the maize-based (gluten-free) diet responded well to parenteral immunization with each of six gluten-derived protein preparations (whole gliadin, two omega-gliadin fractions, wheat salt-soluble proteins, a peptic-tryptic digest and a subtilisin digest of gluten), as serum antibody levels increased at least 300-fold in each case. In contrast, mice raised on the wheat-based diet responded poorly to immunization with either whole gliadin or omega-gliadin and were virtually non-responsive to enzymic digest of gluten. Diet had little effect on the magnitude of the antibody response to wheat salt-soluble proteins, with both groups showing a 300-fold increase in titre. Similarly, tolerance to alpha-zeins, the alcohol-soluble proteins of maize, did not occur on either diet. However, some oral tolerance was observed to maize glutelin. The specificity of the various antibody responses was then analysed by immunoblotting. Following immunization with gluten proteins or digests, antibodies from the maize-fed mice bound more or less equally to each of the main gliadin bands and to the glutenins while the mice on the wheat-based diet had antibody specific for omega-gliadin proteins. Serum antibodies from the maize-fed mice, immunized with either alpha-zein or maize glutelin, showed even labelling of the major maize endosperm proteins while antibodies from mice on the wheat diet showed strong labelling of the Mr 27,000 and 58,000 bands. These results show that diet influenced the specificity, as well as the magnitude of serum antibody responses to cereal proteins. In addition, oral tolerance appeared to affect the humoral response to some cereal proteins more than others. Both of these findings have important implications for our understanding of coeliac disease.

Restriction fragment length polymorphism in HLA class II genes of Latin-American Caucasian celiac disease patients

In the present study Latin-American celiac disease patients were analyzed for the frequency of certain HLA class II restriction fragment length polymorphisms in order to investigate whether they exhibited the normal associated alleles or showed unusual class II variants. A DPB/RsaI 4.0-kb fragment that was shown to be significantly increased among North Americans celiac disease patients of the DR3,DQw2 haplotype was found with similar frequency in Latin-American control and celiac disease individuals. A DPA/BglII 3.7-kb fragment previously shown to be increased among British celiac disease patients was also present with similar frequency among Latin-American control and celiac disease individuals. These results show that the frequency of the HLA-DP region-derived restriction fragment length polymorphisms linked to celiac disease differs between Caucasian populations of different ethnic backgrounds (Anglo-Saxon and Latin-American). On the other hand, DNA samples from 13 patients and 14 controls bearing the DR5/DR7 phenotype (which is significantly associated with celiac disease in Latin populations) were investigated for the presence of particular restriction fragment length polymorphisms disproportionally present in celiac disease individuals. No significant differences were found between controls and patients when the DNA was analyzed with 10 different restriction enzymes and probes for DRB, DQA, DQB, and DPB HLA class II sequences.

Immunopathogenesis of celiac disease

The immunopathogenesis of celiac disease requires interactions between genetic, environmental and immunologic factors. Genes within the class II region of the major histocompatibility complex (HLA-D region) represent a major component contributing to disease susceptibility. Structural studies of genes within the HLA-D region have shown that the class II HLA haplotype associated with celiac disease is extended, and includes not only the HLA-DR and DQ subregions, but also the HLA-DP subregion. The celiac disease-associated haplotype is marked in the HLA-DP subregion by a polymorphic 4 kilobase Rsa I genomic fragment derived from a DP beta chain. Other studies suggest that, in addition to dietary gliadins, a viral protein may play a role in the pathogenesis of celiac disease, perhaps by virtue of immunologic cross reactivity between antigenic determinant shared by the viral protein and alpha gliadins.

Brush border membrane vesicles formed from human duodenal biopsies exhibit Na+-dependent concentrative L-leucine and D-glucose uptake

The human duodenum actively transports L-leucine and D-glucose under Na+ gradient conditions as demonstrated by uptake studies using brush border membrane vesicles from organ donor duodenum. Brush border membrane vesicles formed from peroral duodenal biopsies likewise demonstrate Na+ dependent concentrative uptake of D-glucose and L-leucine. This is the first demonstration of active transport processes in human duodenum. A simple microvesiculation method to form these vesicles is described as well as its potential application to clinical medicine in studying diseases of defective intestinal transport.

An extended HLA-D region haplotype associated with celiac disease

Celiac disease has one of the strongest associations with HLA (human leukocyte antigen) class II markers of the known HLA-linked diseases. This association is primarily with the class II serologic specificities HLA-DR3 and -DQw2. We previously described a restriction fragment length polymorphism (RFLP) characterized by the presence of a 4.0-kilobase Rsa I fragment derived from an HLA class II beta-chain gene, which distinguishes the class II HLA haplotype of celiac disease patients from those of many serologically matched controls. We now report the isolation of this beta-chain gene from a bacteriophage genomic library constructed from the DNA of a celiac disease patient. Based on restriction mapping and differential hybridization with class II cDNA and oligonucleotide probes, this gene was identified as one encoding an HLA-DP beta chain. This celiac disease-associated HLA-DP beta-chain gene was flanked by HLA-DP alpha-chain genes and, therefore, was probably in its normal chromosomal location. The HLA-DP alpha-chain genes of celiac disease patients also were studied by RFLP analysis; 84% of HLA-DR3, -DQw2 patients had a 16-kb Xba I fragment that was present in only 36% of HLA-DR3, -DQw2 controls. Moreover, 79% of these patients had both alpha- and beta-chain polymorphisms in contrast to 27% of controls. Thus, celiac disease is associated with a subset of HLA-DR3, -DQw2 haplotypes characterized by HLA-DP alpha- and beta-chain gene RFLPs. Within the celiac-disease patient population, the joint segregation of these HLA-DP genes with those encoding the serologic specificities HLA-DR3 and -DQw2 indicates: (i) that the class II HLA haplotype associated with celiac disease is extended throughout the entire HLA-D region, and (ii) that celiac-disease susceptibility genes may reside as far centromeric on this haplotype as the HLA-DP subregion.

Intestinal immunity and inflammation: recent progress

The previous sections illustrate that we are still defining (a) which sets of lymphoid cells are present in the intestine and which are not, (b) which sets are peculiar to the intestine, and (c) how the sets that are there function in the intestinal microenvironment. An understanding of the latter point is going to require knowledge of how these sets communicate with and regulate one another via cell surface molecules such as MHC class I and class II molecules, and via soluble mediators or lymphokines. The recent advances in various technologies make this a particularly exciting time in this field because the tools are now available to address and answer some of these basic and important questions in mucosal immunology. At the same time these advances hold great promise for our eventual understanding of chronic inflammatory diseases of the intestine. As was mentioned at the outset, the immune system has considerable power for both protection and destruction. It remains a puzzle how this latter potential is contained and controlled in the intestine of most individuals, such that they do not have inflammatory disease even in the setting of intense stimulation by substances, such as endotoxin, that are phlogistic elsewhere in the body. An answer to the question of why everyone does not have intestinal inflammation could provide new insights into the mechanisms involved in chronic intestinal inflammatory diseases. The recent advances just detailed, as well as others sure to come, suggest that it is only a matter of time before such questions are answered.

An HLA-D region restriction fragment length polymorphism associated with celiac disease

This study is the first to describe a molecular marker that distinguishes the celiac disease HLA-D region haplotype from a serologically identical haplotype in unaffected controls. Using a DQ beta chain cDNA probe and the restriction endonuclease Rsa I, we have detected a polymorphic 4.0 kb fragment which, in DQw2 individuals, is associated with a 40-fold increased relative risk of developing celiac disease. This finding should permit the identification of the celiac disease susceptibility gene(s) in the HLA-D region and facilitate a more precise dissection of the molecular and immunogenetic mechanisms involved in the pathogenesis of that disease.

Antigenicity of native and modified Kunitz soybean trypsin inhibitors

Food provides a continuous antigenic stimulus to the immune system and the antigenicity of processed food proteins should be considered in toxicological evaluations. The antigenicity of the Kunitz trypsin inhibitor was studied using antibodies prepared by inoculating rabbits with native, heat-denatured, and N-acetylcysteine-treated Kunitz soybean trypsin inhibitors. Immunochemical studies using a competitive solid-phase enzyme immunoassay and two groups of sera revealed two patterns of antigenicity. Antibodies elicited with the denatured inhibitor were specific for the denatured conformation of the protein. In contrast, native inhibitor elicited antibodies that selectively recognized determinants in both native and heat-treated protein, but that did not bind trypsin inhibitors treated with N-acetylcysteine. These results imply that: the disulfide bonds must be intact to maintain the native antigenic conformation and the cysteine treatment may suppress allergic manifestations of soybean trypsin inhibitors and possibly other food proteins. These studies were extended by analyzing a panel of monoclonal antibodies prepared against native Kunitz trypsin inhibitor. The inhibitor has at least two distinct antigenic sites (epitopes), one of which is retained under denaturing conditions. The measurement of native Kunitz trypsin inhibitor in food samples by immunoassay appears practical. The relevance of these findings to food processing, food safety, and health is also discussed.