Biomedical subjects
Publications and source records attributed to J N Leonard.
A patient with dermatitis herpetiformis (DH) developed abnormal liver function tests and was found to have histological features of primary sclerosing cholangitis (PSC) on liver biopsy. The association of DH and PSC has not been previously reported and the high incidence of phenotype HLA B8 and DR3 in these disorders suggests a common genetic predisposition may exist for both diseases.
Dermatitis herpetiformis (DH), is associated with skin eruptions and granular depositions of IgA in the papillary dermis, but this is not a feature of coeliac disease (CD). The specificity of the IgA in the skin is unknown. High molecular weight glutenin (HMW-g), a component of gluten, has been shown to have structural similarities to human elastin. This paper reports immunoadsorption studies which suggest that human serum may contain antibodies which cross-react with HMW-g and elastin. DH patients had significantly lower levels of IgA antibodies to HMW-g and to elastin than both CD patients and healthy controls. Furthermore, introduction of a gluten-free diet (GFD) was associated with a further reduction in the amount of IgA antibodies to elastin in the DH patients. This diet-associated decrease of elastin antibodies was restricted to the IgA isotype. A significant correlation was observed between IgA antibodies to HMW-g and elastin in healthy controls and CD patients, while no such correlation was found in patients with DH. These findings could indicate that HMW-g induces production of antibodies to elastin, which are deposited in the skin, and that when the antigenic stimulus is removed, these antibodies are further reduced due to continuous dermal deposition. It is postulated that DH may be an autoimmune disease due to cross-reactivity between dietary glutenin and dermal elastin.
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Lichen planus is a relatively common inflammatory dermatosis with characteristic lesions affecting the skin, nails and mucous membranes. Nail changes are present in approximately 10% of patients and can occasionally occur in the absence of skin involvement. The association of lichen planus with primary biliary cirrhosis is now well recognized. We report the first case of lichen planus confined to the nails in a patient with primary biliary cirrhosis.
One-hundred and sixty-eight cases of dermatitis herpetiformis were reviewed to compare the clinical response to and incidence of side-effects from dapsone and sulphamethoxypyridazine. Thirty-seven received sulphamethoxypyridazine (0.25-1.5 g/day) as a single agent therapy at some stage during their care and 161 had dapsone only (50-450 mg/day). Thirty of these patients received both drugs, but at different times. Both were highly effective in controlling the skin disease in 97% of patients on dapsone and 89% on sulphamethoxypyridazine. While 36 (22%) of dapsone-treated subjects had intolerable side effects warranting a change in therapy, this occurred in only five (13.5%) of those treated with sulphamethoxypyridazine. Sulphamethoxypyridazine was also effective as a single agent in three patients with linear IgA disease who had suffered adverse effects from dapsone, and in 10 out of 15 patients with oral and cutaneous lesions of cicatricial pemphigoid.
Differential absorption of D-xylose and 3-0-methyl-D-glucose, and unmediated intestinal permeation (simple diffusion) of lactulose and L-rhamnose, have been investigated in 20 patients with dermatitis herpetiformis. Both iso-osmolar and hyperosmolar test solutions were employed and the results were compared with those obtained from a group of healthy adult volunteers. The findings in each patient have been correlated with small intestinal histology. The majority of patients with villous atrophy had abnormally raised intestinal lactulose permeation and lactulose/rhamnose permeability ratios, whereas patients with normal small intestinal morphological grading did not differ significantly from the healthy control group in this respect. There was a high incidence of delayed plasma D-xylose absorption peaks in dermatitis herpetiformis irrespective of small intestinal histological findings. These results imply that abnormal intestinal permeability in dermatitis herpetiformis is the result of gluten-induced damage to the mucosa rather than an inherent primary defect. It is therefore improbable that the rash in this condition is purely a manifestation of increased intestinal permeation of antigen.
Twenty nine patients with cicatrizing conjunctivitis were studied; 17 with a clinical diagnosis of cicatricial pemphigoid, five with a clinical diagnosis of pseudopemphigoid caused by long-term application of topical medication and seven who had a cicatrizing conjunctivitis from other causes. Biopsies from clinically uninvolved bulbar conjunctiva were taken for direct immunofluorescence and blood was taken for indirect immunofluorescence using normal human conjunctiva, oral mucosa and skin as substrates. On direct immunofluorescence, in vivo bound immunoglobulins were found along the basement membrane in 10 of the 17 patients with cicatricial pemphigoid, one of the five with pseudopemphigoid and two of the seven with a cicatrizing conjunctivitis associated with other diseases. Circulating anti-basement membrane zone antibodies were found only when conjunctiva was used as a substrate. These were present in seven of the patients with cicatricial pemphigoid, three of those with pseudopemphigoid and two of those with a cicatrizing conjunctivitis caused by other diseases. These results indicate that direct immunofluorescence is a useful, but not absolute diagnostic marker for ocular cicatricial pemphigoid. The results in the pseudopemphigoid group argue that this is an immunologically mediated disorder indistinguishable from spontaneous cicatricial pemphigoid and probably triggered by the drugs. The presence of circulating antibodies should allow for precise identification of the antigen involved in cicatricial pemphigoid using SDS electrophoresis and Western blot analysis.
The prevalence of IgG class thyroglobulin and microsomal antibodies, estimated using a sensitive ELISA, was 48% in 115 patients with dermatitis herpetiformis, which was significantly greater than the prevalence of 16% in 107 unselected controls without dermatitis herpetiformis. IgA class thyroid antibodies were found in 29% of dermatitis herpetiformis patients. Overt thyroid disease had been diagnosed in six (5%) of the dermatitis herpetiformis group and a further six patients had elevated TSH levels. The presence of thyroid antibodies was not associated with particular HLA-DR antigens. These results demonstrate the frequent occurrence of thyroid antibodies in dermatitis herpetiformis, although thyroid failure is less commonly associated with this condition. Immune response genes outside the HLA-DR region may be involved in the immune hyper-responsiveness seen in dermatitis herpetiformis which is reflected in the high prevalence of thyroid autoimmunity.
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The distribution and activation of T-lymphocyte subsets in the small intestinal mucosa of coeliac disease and dermatitis herpetiformis subjects on a normal diet has been studied and compared to normal controls. Double-labelling immunofluorescence techniques with monoclonal antibodies were used on cryostat tissue sections. Intestinal epithelial cells demonstrated staining for HLA-DR, the intensity being proportional to the degree of enteropathy. In both patients and controls nearly all (97%) intra-epithelial lymphocytes were of the CD8 subset and not activated as judged by HLA-DR expression. In the lamina propria there was an approximate 50-fold increase in T cells in the patients as compared with the controls. Whilst the ratio of total CD4 to total CD8 cells was unchanged, the CD4 subset was preferentially activated in the patients. Thus in the normal controls the median ratio of activated CD4 cells to activated CD8 cells was 1.67 whilst for dermatitis herpetiformis and coeliac disease it was 3.42 and 6.07 respectively. These findings suggest that the lamina propria is a site of vigorous T-cell activity in gluten-sensitive individuals and is consistent with the view that the enteropathy of dermatitis herpetiformis and coeliac disease is the result of a delayed-type hypersensitivity against gliadin.
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It has previously been reported that gliadins bind to reticulin in tissue sections. Three lines of evidence are reported in this study which indicate that the gliadins bind to reticulins because they are lectins which bind to sugars expressed on glycoproteins in reticulin and other sites. First, immunofluorescence studies on tissue sections showed that although gliadin binding is largely confined to areas rich in reticulin, it is, nonetheless, also seen in one or two other sites devoid of reticulin. Second, by using fluorescein-labelled lectins of known specificity, it has been shown that the areas to which gliadins bind in tissue sections (including those sites devoid of reticulin) are rich in particular sugars. Third, it has been shown that one of these sugars, alpha-D-mannose, partially inhibited gliadin binding to tissue sections.
Sequential skin biopsies from six patients with severe psoriasis were studied during treatment with cyclosporin. Four of the patients cleared completely and the remaining two showed a marked improvement. A subset of dendritic cells, HLA-DR+ but lacking the T6 antigen characteristically expressed by Langerhans cells (DR+ 6-), was observed in lesional epidermis. They disappeared during treatment, before clinical improvement was apparent and at a rate which correlated with clearance of psoriasis. These cells were not found in normal or uninvolved psoriatic epidermis and their number in lesional skin appeared to be related to the clinical severity of the disease. Total numbers of CD4 and CD8, and HLA-DR+ CD8 T cells were substantially reduced in both epidermis and dermis prior to clinical improvement. In contrast, there was generally no decrease in the number of HLA-DR+ CD4 T cells in the epidermis during resolution, whereas these cells were reduced by an average of 68% in the dermis. The beneficial effects of cyclosporin in psoriasis further support the hypothesis that T cells play a central role in the pathogenesis of psoriasis. The cellular changes observed in the skin during cyclosporin treatment may help to elucidate the effects of this drug on immunoregulatory mechanisms in man.
We have investigated DNA polymorphism of the class II alpha chain genes in HLA typed patients with insulin dependent diabetes mellitus (IDDM; n = 79), celiac disease (CD; n = 46), dermatitis herpetiformis (DH; n = 53), and controls (n = 86). Preferential allelic associations of HLA genes and gene products have thus been constructed for susceptibility to these diseases. DR alpha and DQ alpha gene polymorphisms indicated heterogeneity of HLA DR3, DRw6, and DR7, and HLA DR2 and DRw6, respectively. In DR7 positive CD patients a 3.8-kilobase (kb) DR alpha fragment, which correlated with DQw3, was found in only 11% of patients compared with 45% of corresponding controls (P less than 0.05). An increased frequency of a DX alpha genotype UU in all three diseases was found (IDDM 59%, DH 45%, CD 48%, compared to 21% in controls, P less than 0.001), which is not explained solely by the increased frequencies of DR3-DX alpha U. We therefore conclude part of the genetic susceptibility for these three conditions is encoded by genes within the DQ-DX subregion.
A study was undertaken to determine whether the skin eruption of linear IgA disease (LAD) was gluten dependent. Six patients with LAD were treated with a gluten free diet (GFD) for an average period of 33 months (range 19-48). Although one patient with LAD had an enteropathy which was clearly gluten sensitive, there was no convincing evidence that the rash of any of the patients responded to a GFD. Four of the six patients showed no significant alteration in their drug requirements. The remaining 2 patients showed a fall in minimum drug requirement but there was no increase after gluten challenge indicating that they were entering spontaneous remission. This contrasts to the situation in dermatitis herpetiformis, where both the rash and the enteropathy are gluten dependent. These data add further to the evidence that LAD and dermatitis herpetiformis are separate entities.
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