Characterization of the mucosal immune response to dietary antigens in patients with dermatitis herpetiformis

The association of dermatitis herpetiformis (DH) with granular IgA deposits at the dermal-epidermal junction and a gluten sensitive enteropathy (GSE) suggests that a mucosal immune response may play an important role in the pathogenesis of DH. The degree of antigenic restriction, the immunoglobulin class and subclass response to dietary antigens, and the relationship of antibodies against dietary antigens to IgA-containing circulating immune complexes (CIC) in patients with DH, however, are not known. We have examined the serum of 33 patients with DH for IgG and IgA antibodies against gliadin, and against 3 dietary proteins not thought to be related to GSE, beta-lactoglobulin (beta-lacto), bovine gamma globulin (BGG), and casein. Eleven of 33 (33%) patients with DH had IgA anti-gliadin antibodies, whereas IgA antibodies against beta-lacto were found in 11 of 33 patients (33%), against BGG in 15 of 32 (47%), and against casein in 6 of 33 (18%); 17 of 32 (53%) patients had IgA antibodies against one or more of these dietary antigens. Significantly higher levels of IgA antibodies were detected against beta-lacto (2,500 +/- 2,320 ng/ml, mean +/- SEM) and BGG (2,340 +/- 1,890 ng/ml) than gliadin (1,250 +/- 851 ng/ml) in this group of antibody positive patients (p less than 0.05, Wilcoxon signed ranks test). Eleven of 17 patients with IgA antibodies against dietary antigens were found to have IgA-containing CIC, whereas only one of the 15 antibody negative patients had IgA-containing CIC (p = 0.0008, Fisher's exact test). IgA anti-gliadin antibodies were found to contain both IgA1 and IgA2 with a significantly increased proportion of IgA2 when compared with the IgA2 composition of the total serum IgA (IgA2: anti-gliadin antibodies = 34 +/- 4.2%; total serum IgA = 19 +/- 4.8%, p = 0.02, Students paired t test). IgG antibodies against these antigens were found to occur slightly more frequently in amounts not significantly greater than IgA antibodies. This data demonstrates that a serum IgA and IgG antibody response to dietary antigens occurs in approximately 50% of DH patients with a higher proportion of IgA2 than total serum IgA and does not appear to be restricted to gliadin. This is significantly different from the pattern of cutaneous immunoreactants in patients with DH, and suggests that the deposition of IgA in DH skin may be the result of an atypical mucosal immune response, a non-immunologic interaction of IgA1 and DH skin, or arise from a non-mucosal source.     

TCR Vbeta expression in the small bowel of patients with dermatitis herpetiformis and gluten sensitive enteropathy. Limited expression in dermatitis herpetiformis and treated asymptomatic gluten sensitive enteropathy

Dermatitis herpetiformis (DH) is a blistering skin disease characterized by cutaneous deposits of IgA and an associated, most often asymptomatic, gluten sensitive enteropathy (GSE). Gluten sensitive enteropathy is also seen in patients that do not have skin disease or cutaneous IgA deposits, but do have significant gastrointestinal (GI) complaints. Patients with DH and with GSE without skin disease have similar small bowel morphologic changes and HLA associations and both the skin disease and the GI symptoms can be controlled by a gluten free diet. It is not known what factors allow almost all patients with DH to continue to eat gluten and not develop symptomatic gastrointestinal disease. We have examined the expression of the Vbeta T-cell receptor (TCR) in the small bowel of patients with DH (n=11) and of patients with both symptomatic (n=10) and asymptomatic (n=7) GSE without skin disease to determine if differences in the pattern of TCR Vbeta expression are associated with differences in the clinical manifestations of these diseases. TCR Vbeta expression was analyzed using RT-PCR from small bowel biopsies. Patients with DH and those with GSE without skin disease that were on a gluten free diet and asymptomatic were found to express 6.6 and 5.6 out of 20 Vbeta families respectively, with no single family preference. Examination of peripheral blood lymphocytes from these patients did not reveal any restriction of TCR Vbeta family expression. In contrast, patients with symptomatic GSE expressed 12.6 Vbeta families (P< 0.05), with no consistent preferential expression of any single Vbeta family between patients. Patients with DH, who are continuing to ingest wheat, show a more restricted pattern of TCR Vbeta utilization, similar to that of treated patients with GSE without skin disease, and significantly different from GSE without skin disease patients eating gluten. These findings suggest that the restricted nature of the TCR Vbeta expression may play a role in the different clinical manifestations of dermatitis herpetiformis and isolated gluten sensitive enteropathy.     

Serum antibodies to wheat germ agglutinin and gluten in patients with dermatitis herpetiformis

Summary It has been speculated that gluten may play a role in the pathogenesis of dermatitis herpetiformis (DH) because it can act as a lectin. The lectin activity of gluten preparations was recently identified as wheat germ agglutinin (WGA). IgG and IgA serum antibodies to WGA and gluten were therefore measured in patients with DH and coeliac disease (CD) by an enzylac-linked immunosorbent assay (ELISA). Compared with healthy controls, both patients categories had increased IgG and IgA activities to WGA and gluten, the CD group showing the highest antibody levels. DH patients with subtotal villous atrophy tended to have higher activities than those with no villous changes or only minor changes. No significant difference in the gluten-to-WGA ratio of IgA or IgG antibodies was found when DH patients were compared with CD patients. If WGA plays a pathogenetic role in DH, then DH patients must have dermal characteristics, as yet undefined, that explain the initiation of their skin disease.     

Juvenile dermatitis herpetiformis: an immunoelectron microscopic study

Three children with persistent maculopapular and urticarial lesions and vesicles at the predilection sites of dermatitis herpetiformis (DH) were shown to exhibit typical granular, papillary IgA and C3 deposits in the tips of the dermal papillae, as demonstrated by direct immunofluorescence. By immunoelectron microscopy, the IgA deposits were associated with the microfibrils of the elastic fibres as has been described in DH of the adult. C3 deposits were scattered throughout the papillary dermis. Despite the similarity of the clinical appearance, history with regard to gluten sensitive enteropathy (GSE) varied in these three cases. In one child, the skin lesions appeared following faults in the gluten free diet on which he was kept for coeliac disease. Another child developed the skin lesions during a gluten free diet which was not strictly followed; no recurrences of gastrointestinal symptoms accompanied the eruption of DH. In the third case, no evidence for GSE in patient's history or in jejunal biopsies was present at the time of onset of DH.     

Failure of intradermal skin testing with gluten to produce delayed hypersensitivity reactions in patients with dermatitis herpetiformis

Dermatitis herpetiformis (DH) is characterized by a rash and a gluten-sensitive enteropathy (GSE) indistinguishable from that of coeliac disease. T-cell-mediated mechanisms have been implicated in the pathogenesis of GSE. It seems feasible that intradermal injection of gluten, in patients known to have GSE, could lead to an influx of T cells sensitized to gluten, with subsequent development of a delayed hypersensitivity-type reaction. Six patients with DH and three normal subjects had intradermal injections of‘Frazer's fraction III’ (FFIII; the partial peptic tryptic digest of gluten which is known to be antigenic) and phosphate-buffered saline (PBS) as a control. Skin biopsies were taken at PBS and FFIII injection sites at 48 h. In addition, two of the patients with DH had biopsies taken of FFIII injection sites at 6 h. Monoclonal antibodies and the avidin-biotin-peroxidase technique were used to stain for T cells in the skin biopsies. A monoclonal antibody to a neoepitope exposed in the terminal complement complex and an immunofluorescent method were used to detect the presence of terminal complement component in biopsies taken from two of the control subjects and two of the patients. Both patients and control subjects developed a weal and flare within a few minutes of injecting the FFIII, and this persisted for up to 6 h. No skin reaction was present in either the patients or the control subjects at 48 h. No skin reaction was visible at any time following injection of PBS. There was no increase in T cells in biopsies taken at 6 or 48 h from the FFIII injection sites compared with the PBS injection sites. Terminal complement component was present in the biopsies taken from DH patients at both the PBS and FFIII injection sites (6 and 48 h), but was absent from the biopsies taken from the control subjects. Normal delayed hypersensitivity responses to a battery of common recall antigens showed that the lack of response to FFIII was antigen specific. Thus, this study suggests that the T cells sensitized to gluten in patients with GSE are unable to migrate to the skin.     

A comparison of histocompatibility antigens in dermatitis herpetiformis and adult coeliac disease

The incidence of histocompatibility antigens HL-A, 4a and 4b was studied in thirty-eight patients with dermatitis herpetiformis (DH) and thirty-six patients with adult coeliac disease (ACD). The 4b antigen was found in all the DH and ACD patients. HL-A 8 was found in 89% of patients with ACD--similar to the incidence reported in previous studies--and in 79% of patients with DH, a higher incidence than in previous studies which may be due to stricter criteria being used here to diagnose DH. There was no significant difference in the incidence of HL-A 8 between those patients with DH whose small intestinal biopsies appeared macroscopically abnormal and those with a normal macroscopic appearance. These findings suggest that patients with DH form a single disease group and do not support the concept previously postulated that there are two groups of patients with DH, one with an increased incidence of HL-A 8 antigen similar to that in ACD who have a gluten sensitive enteropathy (GSE), and another with a normal incidence of HL-A 8 antigen and without enteropathy.     

The effect of an elemental diet with and without gluten on disease activity in dermatitis herpetiformis

Elemental diets are reported to decrease activity of patients with dermatitis herpetiformis. We tested the hypothesis that gluten, given in addition to an elemental diet, is responsible for the intestinal abnormalities, cutaneous immunoreactant deposition, and skin disease activity in dermatitis herpetiformis. At entry eight patients with dermatitis herpetiformis, who were consuming unrestricted diets, were stabilized on their suppressive medications at dosage levels that allowed individual lesions to erupt. Six patients were then given an elemental diet plus 30 of gluten for 2 weeks, followed by the elemental diet alone for 2 weeks. Conversely, two patients received an elemental diet alone for 2 weeks followed by an elemental diet plus gluten during the final 2 weeks. Small bowel biopsies, skin biopsies, and clinical assessments were done at 0, 2, and 4 weeks. Suppressive medication dose requirement decreased over the 4 weeks by a mean of 66%. Six of eight subjects significantly improved clinically during the gluten-challenge phase of the elemental diet and all were improved at the end of the study. The amount of IgA in perilesional skin did not change significantly, but the amount of C3 increased in five of seven evaluable subjects after gluten challenge. Circulating anti-gluten and anti-endomysial antibodies were not significantly affected by the diets. All subjects completing evaluable small bowel biopsies (seven of seven) demonstrated worsening of their villus architecture (by scanning electron microscopy and intraepithelial lymphocyte counts) during gluten challenge and improvement (six of six subjects) after 2 weeks of elemental dietary intake. We conclude that 1) there is a significant improvement in clinical disease activity on an elemental diet, independent of gluten administration, 2) small bowel morphology improves rapidly on an elemental diet, and 3) complement deposition but neither IgA deposition nor circulating antibody levels correlate with gluten intake. It seems likely that dietary factors other than gluten are important in the pathogenesis of the skin lesions in dermatitis herpetiformis.     

IgA anti‐epidermal transglutaminase autoantibodies: a sensible and sensitive marker for diagnosis of dermatitis herpetiformis in adult patients

Background Dermatitis herpetiformis (DH) is a rare gluten‐sensitive blistering itchy skin disease, strictly related to coeliac disease (CD). Direct immunofluorescence, demonstrating IgA granular deposits localized either in the dermal papillae or along the dermo‐epidermal junction, is currently the gold standard for diagnosis of DH. It has been shown that DH immunocomplexes contain epidermal transglutaminase (eTG) and that sera from patients with DH contain antibodies specifically directed against eTG. Objectives We studied the usefulness of serum eTG antibodies in discriminating between DH, CD and other gastrointestinal and dermatologic diseases. Methods eTG antibodies were tested in 308 adult patients’ sera: 44 patients with untreated dermatitis herpetiformis (UDH), 99 patients with untreated coeliac disease (UCD), 70 dermatological controls and 95 gastrointestinal controls. Results In UDH eTG antibody levels were significantly higher than in DH patients on gluten‐free diet, UCD, gastrointestinal controls and dermatological controls. In UCD eTG antibodies strongly correlated with tissue transglutaminase (tTG) antibodies, whereas in UDH no significant correlation was observed. Conclusion Serum IgA eTG antibody determination can efficiently distinguish UDH from other dermatological itchy diseases and is highly sensitive to gluten‐free diet.     

Serum IL-8 in patients with dermatitis herpetiformis is produced in response to dietary gluten

Patients with dermatitis herpetiformis (DH) have a gluten-sensitive enteropathy and while on gluten-containing diets have elevated levels of serum IL-8. We hypothesized that the mucosal immune response to gluten is responsible for the elevated serum IL-8. Six DH patients were studied while on a gluten-free diet (GFD), whereas four continued on a normal diet. Patients were followed for a mean 2.2 years and serum IL-8 was analyzed. Small bowel biopsies from five DH patients on normal diets, two DH patients on GFD, and six subjects with no small bowel abnormalities were analyzed for IL-8 mRNA. Serum IL-8 levels normalized in five of six patients on GFD and decreased in one, whereas serum IL-8 levels showed no statistically significant change in DH patients on normal diets. Small bowel biopsies from DH patients on normal diets had increased expression of IL-8 mRNA compared to normal subjects, whereas patients on a GFD showed no significant increase in small bowel mRNA. No significant IL-8 mRNA was detected in normal skin biopsies from patients with DH. These observations suggest that the IL-8 in the serum of patients with DH originates from the small bowel as a mucosal immune response to gluten ingestion.     

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

Summary A sensitive and technically simple enzymelinked 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.Supported by grants from the Foundation for Finnish Chemical Research     

An HLA class II region restriction fragment length polymorphism (RFLP) in patients with dermatitis herpetiformis: association with HLA-DP phenotype

Dermatitis herpetiformis (DH) is characterized in part by an associated gluten-sensitive enteropathy (GSE), and a strong association with the HLA antigens HLA-A1, -B8, -DR3, and -DQw2, essentially identical to that seen in patients with isolated GSE (celiac disease). A 4.0-kb RsaI RFLP has been identified using a DQ beta-chain cDNA and localized to the HLA-DP beta-chain region. This RFLP has been found more frequently in patients with isolated GSE than in normal HLA matched controls. We have analyzed genomic DNA from 24 patients with DH and 15 HLA-matched controls to determine if this 4.0-kb RsaI RFLP was present in patients with DH. Twenty-one of 24 (87%) of patients with DH were found to have this RFLP as compared to 7 of 10 (70%) HLA-DR3, -DQw2 matched control subjects (p = 0.23). Thus, the 4.0-kb RsaI RFLP detected in patients with isolated GSE is also present in patients with DH; however, its frequency in DH patients does not differ significantly from that of HLA matched controls. Family studies of patients with DH revealed that although the 4.0-kb RsaI RFLP segregated with the HLA-A1, -B8, -DR3, -DQw2 haplotype in one family, it did not segregate with this disease-associated haplotype in two other families. In both patient and control populations, this RFLP was associated with HLA-DPw1 or -DPw3 phenotypes; 25 of 26 (96%) HLA-DPw1 or -DPw3 subjects were found to have this RFLP compared to only 1 of 6 (17%) who did not express HLA-DPw1 or -DPw3 (pc = 0.0009). These population and family data suggest that this 4.0-kb RsaI RFLP is primarily associated with the HLA-DPw1, -DPw3 phenotype, rather than the clinical manifestations of DH. These data further document that the strongest association of DH with HLA antigens remains with HLA-DQw2 and HLA-DR3 antigens.     

Transglutaminase autoantibodies in dermatitis herpetiformis and celiac sprue

Dermatitis herpetiformis (DH) is an autoimmune blistering skin disorder that is associated with intestinal gluten sensitivity. Epidermal transglutaminase (TGe) and closely related tissue transglutaminase (tTG) are considered to be autoantigens in DH, because a majority of DH patients have IgA specific for TGe and for tTG. It is unknown where and how these autoantigen-specific IgAs are generated in DH. Results reported in this paper on nine DH patients on a gluten containing diet demonstrate that the levels of circulating anti-tTG IgA and anti-TGe IgA in DH are correlated with each other and that both appear to be correlated with the degree (extent) of enteropathy. An analysis of 15 untreated celiac sprue (CS) patients demonstrated that approximately 33% of CS patients had elevated levels of anti-TGe IgA. These results would indicate that intestinal damage is associated with the production of anti-tTG IgA and anti-TGe IgA in DH patients.     

Dietary management of dermatitis herpetiformis

Dermatitis herpetiformis (DH) is an extremely itchy, papulovesicular skin disease characterized in part by the presence of IgA at the dermal-epidermal junction. Eighty-five percent to 90% of DH patients have granular deposits of IgA at the dermal-epidermal junction, and essentially all of these patients have an associated, for the most part asymptomatic, gluten-sensitive enteropathy (GSE). The association of GSE and DH suggested that the cutaneous manifestations of DH could be controlled by the use of a gluten-free diet. Institution of a gluten-free diet in patients with DH and granular IgA deposits has been shown to be effective in controlling the cutaneous eruption of DH. Seventy percent to 100% of patients who begin a strict gluten-free diet have been shown to be able to decrease the dosage of medication needed to control their DH after a mean of eight to 18 months on the diet. Furthermore, 40% to 70% of patients with DH can control their skin disease completely, without any medication, after longer periods of time on the gluten-free diet (two years and longer). Although the gluten-free diet has been shown to be of great benefit in the control of the skin manifestations of DH, at the present time there is no evidence to suggest that the gluten-free diet is in any way protective against the risk of intestinal lymphoma that has been documented in GSE. Evaluation of the cutaneous IgA deposits in DH skin after long periods of time on a gluten-free diet suggests that there may be a slight decrease in the intensity of the IgA deposits, but the true pathogenetic relationship between the cutaneous IgA deposits, the cutaneous manifestations of DH, and the associated GSE remains unknown.     

Management of dermatitis herpetiformis

The major treatment strategies for DH are gluten restriction or medical treatment with sulfones. Control of the cutaneous manifestations, but not the gastrointestinal changes, is rapid with dapsone. In addition to control of the cutaneous signs and symptoms of DH, dietary gluten restriction also induces improvement of gastrointestinal morphology and is possibly protective against the development of lymphoma.     

Soluble interleukin-2 receptor levels in patients with dermatitis herpetiformis

To determine the role of T-cell activation in dermatitis herpetiformis (DH), soluble IL-2R levels were measured by enzyme-linked immunosorbent assay (ELISA) in the sera of 30 patients with DH. Levels of this shed receptor are considered to be a measure of in vivo T-lymphocyte activation, and are elevated in the sera of many patients with inflammatory and immune-mediated diseases. Fifteen of the thirty (50%) patients with DH had elevated levels of soluble IL-2R compared to one of 31 (3%) healthy HLA-B8 or HLA-DR3 control subjects (p less than 0.00001) and one of 10 (10%) healthy non-HLA-B8/-DR3 subjects (p less than 0.0018). In addition, the mean soluble IL-2R level in the patients with DH (744 +/- 381 U/ml) was also significantly higher than that seen in 31 healthy HLA B8 or HLA DR3 individuals (388 +/- 160 U/ml, p = 0.0001) and 10 healthy non-HLA-B8/DR3 individuals (397 +/- 201 U/ml, p = 0.002). Only two of the 30 patients with DH had active skin lesions at the time of serum sampling, one of whom had elevated levels of IL-2R. Measurement of soluble IL-2R levels in sequential serum samples, available in four patients with DH at times of active and inactive skin disease, demonstrated a temporal association between soluble IL-2R level elevations and active skin disease in two patients and no association in two patients. In one patient a marked elevation in soluble IL-2R levels occurred with the onset of gastrointestinal symptoms, which decreased by 14% with institution of a gluten-free diet. In order to determine if soluble IL-2R levels are related to the mucosal immune response, the IL-2R levels were compared to the level of IgA antibodies directed against the dietary antigen beta-lactoglobulin. Ten of eleven (91%) patients with circulating IgA anti-beta lactoglobulin antibodies were also found to have elevated levels of IL-2R. In contrast, in the patients with no detectable IgA anti-beta lactoglobulin antibodies, only four of 16 (25%) had elevated levels of IL-2R (p = 0.001). Because IL-2R levels are not related to activity of the skin disease in patients with DH but are associated with the presence of IgA antibodies against the dietary antigen beta-lactoglobulin, these results suggest that some of the T-cell activation commonly present in DH reflects an ongoing immune response in the gastrointestinal tract.     

Elevation of IgA anti-epidermal transglutaminase antibodies in dermatitis herpetiformis

Background  Dermatitis herpetiformis (DH) is a papulovesicular eruption caused by ingestion of gluten. It is characterized by the deposition of IgA in the dermal papillae. IgA antibodies directed at tissue transglutaminase (TG2) are elevated in gluten-sensitive diseases including DH and coeliac disease (CD). More recently, antibodies directed at epidermal transglutaminase (TG3) were identified in patients with DH, and this may be the dominant autoantigen in this disease.
Objectives  To measure IgA antibodies to TG3 and TG2 in patients with DH and CD, and control populations.
Methods  Serum IgA antibodies against TG2 and TG3 were measured from adults with DH, adults and children with CD, patients with psoriasis, adult Red Cross blood donors, and paediatric controls.
Results  Patients with DH and CD had elevated levels of IgA anti-TG2 antibodies compared with control populations. The levels in the patients with DH and adults with CD were similar. IgA anti-TG2 antibodies were higher in the children with CD compared with adults with DH and CD, and with control populations. Patients with DH and adults with CD had elevated levels of IgA anti-TG3 antibodies compared with children with CD and control populations. There was a trend towards higher levels in the patients with DH compared with adults with CD.
Conclusions  IgA antibodies to TG3 are elevated in patients with DH and adults with CD. The progressive expansion of the epitope-binding profile of IgA antitransglutaminase antibodies in patients with CD may explain the development of DH in patients with undiagnosed CD during their adult life.     

Two Japanese cases of dermatitis herpetiformis associated each with lung cancer and autoimmune pancreatitis but showing no intestinal symptom or circulating immunoglobulin A antibodies to any known antigens

Dermatitis herpetiformis (DH) is common in some Caucasian populations but extremely rare in Japanese, probably because of different immunogenetic backgrounds. We report two Japanese DH cases with typical clinical, histological and direct immunofluorescence features. However, no symptom of gluten‐sensitive enteropathy was shown. The diagnosis was confirmed by eliminating other autoimmune blistering diseases by indirect immunofluorescence, enzyme‐linked immunosorbent assays and immunoblotting. However, circulating immunoglobulin (Ig)A anti‐endomysium, reticulin and gliadin antibodies were not detected. IgA antibodies to tissue and epidermal transglutaminases were also negative. One case was associated with lung cancer and the other one with autoimmune pancreatitis. On review of 17 cases of DH reported in Japan over the previous 10 years, including our cases, one case was associated with gluten‐sensitive enteropathy, four with malignant neoplasms, two with autoimmune systemic disorders and one with psoriasis. Although our cases were typical of DH in clinical, histopathological and IgA deposit features, they showed different human leukocyte antigen haplotypes, no gluten‐sensitive enteropathy and no DH‐specific IgA antibodies, including those to epidermal and tissue transglutaminases. These results suggest that studies of unique characteristics in Japanese DH patients should facilitate further understanding of pathogenesis in DH.     

Dermatitis herpetiformis: problems,progress and prospects

Dermatitis herpetiformis (DH) is an IgA mediated blistering skin disease characterized by the presence of granular deposits of IgA in papillary dermis. The major significant advances in our understanding of DH have been the demonstration that DH patients also have coeliac diseases (CD) and that the rash is also gluten dependent. As a result, it is now possible to cure patients by gluten withdrawal from the diet. The other major significant finding has been the presence of IgA in the uninvolved, now used as the diagnostic criterion for the disease. Despite the fact that it has been known for over fifty years that gluten causes the enteropathy of CD, and for over thirty years the rash of DH, it is still not known how gluten produces these effects. Future immunological studies may look at ways of inducing tolerance to gluten peptides once the toxic ones have been identified. Vaccination against gluten peptides may also be possible in those affected with gluten sensitive disorders.     

Palmar Purpura: An Atypical Presentation of Childhood Dermatitis Herpetiformis

Abstract: Dermatitis herpetiformis (DH) is seen most commonly as a pruritic, papulovesicular eruption in young children or adolescents. Differentiation from other bullous diseases of childhood may be difficult. We report the first case of an adolescent in whom pruritic, palmar, purpuric macules and papules were the only manifestations of DH. The patient later developed typical vesiculobullous extensor lesions and symptomatic gluten-sensitive enteropathy (GSE). All lesions and GSE symptoms resolved with dapsone and a gluten-free diet. Our purpose is to illustrate an unusual presentation of pediatric DH.     

Dermatitis herpetiformis

The state of our understanding of the pathogenesis of DH relies on the integration of several key characteristics: (1) a high frequency of the HLA antigens HLA-B8, HLA-DR3, and HLA-DQw2, (2) an associated GSE, (3) the resolution of both the skin lesions and gut abnormalities in response to a gluten-free diet, and (4) the presence of granular deposits of IgA in normal and perilesional skin. The role of the HLA class II antigens expressed in patients with DH most likely relates to the afferent or initiating arm of the immune system. The association of the HLA-A1, -B8, -DR3, -DQw2 haplotype with Sjogren's syndrome, chronic hepatitis, Graves' disease, and other presumably immunologically mediated diseases, as well as the evidence that some normal HLA-B8, -DR3 individuals have an abnormal in vitro lymphocyte response to wheat protein and mitogens and have abnormal Fc-IgG receptor-mediated functions, suggests that this HLA haplotype or genes linked closely to it may confer a generalized state of immune susceptibility on its carrier, the exact phenotypic expression of which depends on other genetic or environmental determinants. It also is clear, from the association of DH with GSE and the ability to control the cutaneous manifestations of DH with a gluten-free diet, that the gut disease is a critical factor in the pathogenesis of DH. Several pathogenetic theories about the origin of the cutaneous IgA deposits in DH have been proposed, one of which states that the IgA is produced in the gut mucosa as a response to a dietary antigen or gut epithelial antigen and then cross-reacts with the skin of patients with DH. A second hypothesis is that the IgA produced in the gut binds to an antigen and is deposited in skin as an antigen-antibody complex. Finally, it could be that the gut mucosal abnormality simply allows an unknown antigen access to the central immune system where an IgA antibody is produced that binds to skin. The failure to detect circulating IgA anti-basement membrane zone antibodies in patients with DH suggests that either the structures to which the IgA binds are not present in normal skin without DH, that IgA cannot bind to these structures in vitro, or that the circulating IgA is too scant for detection with conventional methods. Finally, it must be considered that the IgA deposited in DH skin may bind as a result of non-antigen-antibody interactions that cannot be duplicated in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)