Demonstration of antibodies to wheat gliadin in dermatitis herpetiformis using 14C-radioimmunoassay

IgA class antibodies in dermatitis herpetiformis: reaction with tissue antigens

The mechanism for deposition of IgA in dermatitis herpetiformis (DH) remains unclear. To test the hypothesis that a circulating IgA class antibody in DH patients binds to constituents of normal human skin, we employed the highly sensitive methods of immunoblotting and indirect immunofluorescence. Sera from 64 DH patients, 67 randomly selected normal control subjects, 29 histocompatibility locus antigen (HLA) B8/DR3/DQw2 controls, and 12 psoriatic patients were tested for IgA binding to various substrates, including dermal and epidermal extracts, fibroblast and keratinocyte supernatants, monkey esophagus sections, and whole and saline-split normal human skin sections. Significant differences observed among the groups in the frequency of detectable IgA antibodies reacting with various substrates were as follows: 1) IgA antibodies in 30% of both DH and HLA B8/DR3/DQw2 sera bound to a 60-Kd protein in dermal extracts (p less than 0.25 versus non-HLA matched controls); 2) IgA antiendomysial antibodies were present in 38% of DH patients (predominantly those not on gluten-free diets), whereas both normal control groups had frequencies of 5-10% (p less than 0.025); 3) there was more nonspecific IgA antibody-binding to dermal, epidermal, and bovine proteins in DH and HLA control sera than in normal sera; and 4) IgA antibodies directed against the basement membrane were present with an increased frequency of 25% in both DH and HLA B8/DR3/DQw2 sera (p less than 0.1 versus non-HLA matched controls). Therefore, these results do not support the hypothesis that there is an unique antigen within normal human skin to which IgA antibodies from DH sera bind.

The pathogenesis of dermatitis herpetiformis: recent advances

Over the last two decades a rapid expansion of our knowledge regarding dermatitis herpetiformis has occurred, including the discovery of IgA in the skin, the discovery of an associated gluten-sensitive enteropathy, the noting of an increased prevalence of the human lymphocyte antigens (HLA)-B8 and -DRw3, and the documentation that the skin disease of many dermatitis herpetiformis patients can be controlled by a gluten-free diet. It has also been noted that two distinct forms of dermatitis herpetiformis occur, those with granular deposits of IgA at the dermoepidermal junction (85%-95% of dermatitis herpetiformis patients) and those with linear IgA deposits (10%-15% of dermatitis herpetiformis patients). These findings are reviewed with particular emphasis on the form of dermatitis herpetiformis associated with granular IgA deposits. The current findings regarding the nature and origin of the cutaneous IgA deposits, the role of the gluten-sensitive enteropathy, and the spectrum of both the immunologic and the nonimmunologic abnormalities associated with dermatitis herpetiformis are presented, and from these data pathophysiologic mechanisms are proposed that may be involved in dermatitis herpetiformis.

Avidity of antigliadin IgA and IgG antibodies in gluten-sensitive enteropathy and dermatitis herpetiformis

Antigliadin antibodies (AGA) of IgG and IgA class were assayed with a modified enzymeimmunoassay in serum samples of 18 patients with gluten-sensitive enteropathy and 30 patients with dermatitis herpetiformis. No difference between antibody amount or avidity of the two groups of patients was observed. Avidity and total amount of AGA were also compared in 15 patients with a recent diagnosis of dermatitis herpetiformis and in 15 patients with a disease history of several years without a proper gluten-free diet. No difference in IgG antibodies was found but the amount of high avidity IgA antibodies was significantly higher in patients with several years' experience of dermatitis herpetiformis than in those with a recent diagnosis. The results indicate that in dermatitis herpetiformis, maturation of IgA response occurs. Further, clinically, maturation of anti-gliadin IgA response during the disease can increase the sensitivity of the patient against diet-derived gliadin.

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.

Vesicular pemphigoid vs dermatitis herpetiformis

We describe a patient with clinical features of dermatitis herpetiformis (DH) and histopathologic features suggestive of both DH and bullous pemphigoid (BP). Immunofluorescent (IF) studies of skin biopsy revealed IgG and C3 deposits along the basement membrane zone (BMZ) in a linear pattern and circulating BMZ antibodies in the serum consistent with BP. The patient's condition evolved over 5 years into a typical case of DH characterized by histologic findings of papillary edema and neutrophilic infiltrates and evidence by IF findings of granular IgA deposits in the dermal papillae and the presence of antigliadin antibodies in the serum.

Increased gliadin antibodies in dermatitis herpetiformis and pemphigoid

The mean titres of serum IgG and IgA gliadin antibodies were significantly increased in thirty-four patients with bullous pemphigoid, and in twenty-three patients with dermatitis herpetiformis, compared with twenty-four healthy controls. The patients with pemphigoid also had increased IgG and IgA gliadin antibodies compared with nine patients with pemphigus. The reason for the high titres of gliadin antibodies in pemphigoid is obscure. These patients may have increased intestinal permeability (suggested by the presence of beta-lactoglobulin antibodies in some patients). Alternatively gliadin may somehow precipitate the autoimmune process.

Class-specific antibodies to gluten in dermatitis herpetiformis

An immune reaction to wheat protein has been previously proposed to explain the pathogenesis of dermatitis herpetiformis. In order to detect and characterize antibodies to gluten in human sera, we developed an enzyme immunoassay for class-specific antibodies. Results of this assay in 49 patients with dermatitis herpetiformis were compared with those of 38 normal control subjects, 11 patients with celiac disease, and 6 small-bowel bypass patients. IgA antibodies to gluten were significantly more frequent in dermatitis herpetiformis sera (28/49) than in normal control sera (4/38). IgG antibodies to gluten were significantly more frequent in both celiac disease (10/11) and dermatitis herpetiformis (16/49) sera than in control (5/38) sera. Dermatitis herpetiformis sera also had an increased prevalence of IgM antibodies to gluten (19/49). Small-bowel bypass patients demonstrated no antibody to gluten. Antibodies to gluten in dermatitis herpetiformis objectively mark a state of immune reactivity to wheat protein and may be involved in the genesis of the cutaneous IgA immune deposits and the skin disease.

Circulating IgA- and IgG-class antigliadin antibodies in dermatitis herpetiformis detected by enzyme-linked immunosorbent assay

A sensitive and technically simple enzyme-linked immunosorbent assay (ELISA) was developed to demonstrate circulating IgA- and IgG-class antibodies to gliadin, a component of wheat gluten. Serum samples from 24 patients with dermatitis herpetiformis (DH), 5 with coeliac disease (CD) and 75 normal controls were analysed. Antigliadin antibodies (AGA) of the IgA class were detected in 71% of DH patients, all of the CD patients and 19% of the controls. IgG-AGA was found in over 90% of DH patients and controls and in all of the CD patients. The mean ELISA values of both IgA- and IgG-class AGA were significantly higher in DH patients than in the controls. The occurrence of circulating IgA-class AGA is compatible with the hypothesis that these antibodies can be deposited in the skin, e.g. as immune complexes, or due to cross-reactivity of gliadin and dermal reticulin.

Detection of gluten in human sera by an enzyme immunoassay: comparison of dermatitis herpetiformis and celiac disease patients with normal controls

We have developed a triple sandwich enzyme immunoassay to detect circulating gluten in human sera. With human sera containing known amounts of added gluten as controls, the assay was sensitive in the range of 0.75 to 75 micrograms of gluten per ml of serum. Forty-one control subjects were compared to 21 patients with dermatitis herpetiformis and 11 patients with celiac disease. The dermatitis herpetiformis and celiac disease patients had significant elevation of serum gluten values over the control subjects. Circulating gluten antigenemia is a previously unrecognized feature which may be important in understanding the pathogenesis of dermatitis herpetiformis and celiac disease.

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.

Anti-gliadin antibodies in dermatitis herpetiformis

Images

Binding of wheat gliadin in vitro to reticulum in normal and dermatitis herpetiformis skin

We have demonstrated by indirect immunofluorescence that wheat gliadin binds in vitro to reticulin-like fibrils present in cryostat sections of human skin, and rat liver, kidney and stomach. Gliadin was seen to bind to fibrils throughout the dermis of both normal and dermatitis herpetiformis skin, and this was particularly striking in the dermal papillae. Serum from 2 dermatitis herpetiformis patients who did not have antireticulin antibody gave reticulin staining when retested by immunofluorescence on cryostat sections of rat tissue pretreated with gliadin. Gliadin treated sections may prove useful in screening patients with gluten sensitive enteropathy for anti-gliadin antibody. Binding of gliadin to skin sites in dermatitis herpetiformis patients and subsequent deposition of antigliadin antibody at these sites may be involved in the development of skin lesions.

Circulating immune complexes of IgA type in dermatitis herpetiformis

There is some evidence that dermatitis herpetiformis may be mediated by circulating immune complexes. This study attempts to define the antibody class of these complexes. All patients studied demonstrated granular deposition of IgA in the papillary dermis on direct immunofluorescence. Serum immune complexes were detected using the qualitative Raji cell immunofluorescent assay, as well as the quantitative immunoradiometric assay. A group of 25 dermatitis herpetiformis patients was found to have higher levels of IgA containing complexes compared to a group of normals (p < .01). Higher levels of IgG containing complexes were also noted in dermatitis herpetiformis patients at a low level of statistical significance (p < .1). The relationship of these complexes to the pathogenesis of dermatitis herpetiformis is yet to be determined.

Wheat protein antibodies in dermatitis herpetiformis

An enzyme-linked immunosorbent assay was used to detect class-specific antibodies to wheat protein antigens. Antibodies which we detected by this technique reacted indistinguishably with antigens prepared from crude gluten, crude gliadin, alpha-gliadin, Frazer fraction III, and subfraction B and B3 of Frazer fraction III. No sera reacted with a human serum albumin control antigen. The prevalence of IgG antibodies to wheat protein antigens was significantly greater in patients with gluten sensitive enteropathy, 12 of 17, (p = .00011) and in patients with dermatitis herpetiformis, 5 of 14, (p = .046) than in normal control subjects. Strongly positive reactions for IgG antibodies were present only in patients with gluten sensitive enteropathy or dermatitis herpetiformis. IgA antibodies to wheat protein antigens were found only in gluten-sensitive enteropathy patients. We have found this to be a sensitive, precise technique for measurement of antibodies to wheat protein antigens and feel that it will prove useful in evaluation of the role of immune complexes involving wheat protein antigens and their antibodies in the pathogenesis of dermatitis herpetiformis.

Failure to detect gliadin or gliadin binding sites in the skin of patients with dermatitis herpetiformis: immunofluorescence, organ culture and autoradiographic studies

Recent investigations indicate an abnormal binding of gluten or gliadin to lymphocytes or intestinal mucosa cells in gluten sensitive enteropathy. Since dermatitis herpetiformis is closely associated to gluten sensitive enteropathy, similar receptors could also exist in the skin of patients with dermatitis herpetiformis. To prove this hypothesis, skin of normal volunteers and uninvolved skin of 3 patients with dermatitis herpetiformis was investigated for the presence of gliadin and gliadin binding sites. In vivo bound gliadin was not found by direct immunofluorescence using 3 different rabbit antigliadin antisera. In order to test skin for gliadin binding sites, normal sera and autologous dermatitis herpetiformis sera containing 25 mg% gliadin and tritium labeled gliadin, respectively, were used for incubation of normal and dermatitis herpetiformis skin cryocut sections and of normal and dermatitis herpetiformis skin specimens, grown under organ culture conditions. As checked by direct immunofluorescence and autoradiography, there was no specific in vitro binding of gliadin, indicating that gliadin does not fix to normal human or dermatitis herpetiformis skin. Thus, the role of gliadin in the fixation in vivo, of antibodies or immune complexes to skin in dermatitis herpetiformis, remains obscure.