Contact allergies in haemodialysis patients: a prospective study of 75 patients

BACKGROUND

Haemodialysis exposes patients to many potentially sensitizing allergens.

OBJECTIVES

The primary objective of this study was to evaluate the prevalence of delayed hypersensitivity in a population of haemodialysis patients. Secondary objectives were to identify the possible risk factors for contact sensitization and to propose a series of skin tests adapted to haemodialysis patients.

METHODS

A prospective monocentric study was carried out in a nonselected population of haemodialysis patients. For each patient, medical history of atopy and allergic contact dermatitis, ongoing treatments (including topical ones), presence of eczema at the site of vascular access for haemodialysis were recorded. Allergological investigation included delayed hypersensitivity tests (European Environmental and Contact Dermatitis Research Group battery, tests GERDA, additional list and a battery of antiseptics and other dialysis-specific allergens) and latex skin prick test.

RESULTS

Seventy-five patients (41 men, 34 women, mean age of 65 years old), with a mean 3.8 years under dialysis, were included. Nineteen patients (25%) had at least one positive skin test and 13 (17%) a positive patch test to at least one allergen relative to dialysis process including eight tests to lidocaine-prilocaine cream and three to povidone-iodine. Tests results seemed clinically relevant since nine patients had localized pruritus at the fistula site and six patients active eczema around it.

CONCLUSION

Contact sensitizations are frequent in haemodialysis patients and are linked to vascular access conditioning especially the use of lidocaine-prilocaine cream. Designing a specific test battery could help to diagnose the potential allergens and subsequently to give advice to avoid contact with sensitizing agents.

A possible role of prolyl oligopeptidase during Linum usitatissimum (flax) seed development

Involvement of prolyl oligopeptidases (POPs) in the control of several mammalian peptide hormone signalling pathways has been studied extensively in recent years. POPs are ubiquitous enzymes, but little attention has been paid to understanding their function in plants. Using a cDNA-AFLP approach, two flax (Linum usitatissimum) POP ESTs were identified as being specifically expressed in the early stages of flax seed development. This specific expression was confirmed using real time RT-PCR and in situ hybridisation approaches. Seed expression of Arabidopsis POP genes was measured and showed no specificity. Comparison between results obtained with flax and Arabidopsis is discussed in order to address a hypothetic function for POPs during seed formation. These results provide the first insights into POP gene expression and hypothetical function in plants.

The skin allergenic properties of chemicals may depend on contaminants--evidence from studies on coumarin

BACKGROUND/AIMS

Positive patch tests are considered representative of a contact allergy to the tested chemical. However, contaminants and derivatives rather than the suspected chemical itself could be responsible for the allergic skin reactions. Here, we tested the importance of contaminants in the sensitizing and allergenic properties of coumarin in mice and humans. Coumarin, an ingredient in cosmetics and fragrances, was chosen as the reference chemical since conflicting results have been obtained regarding its ability to induce contact allergy. In some chemical preparations, this could be explained by the presence of coumarin derivatives endowed with allergenic properties.

METHODS

In mice, three different coumarin preparations were tested in the local lymph node assay. In humans, we assessed the irritant and allergenic properties of highly pure coumarin in nonallergic and fragrance-allergic patients.

RESULTS

Pure coumarin did not exhibit irritant or sensitizing properties in the local lymph node assay. In contrast, two other commercially available coumarins and three contaminants that were detected in these coumarin preparations were identified as weak and moderate sensitizers, respectively. In humans, pure coumarin was extremely well tolerated since only 1 out of 512 patients exhibited a positive patch test to the chemical.

CONCLUSIONS

These results indicate that coumarin cannot be considered as a common contact allergen and further emphasize that purity of chemicals is mandatory for the assessment of their allergenicity.

[Pathogenesis of atopic dermatitis]

Atopic dermatitis (AD) is a chronic inflammatory dermatosis due to the activation ofT-cell lymphocytes specific to protein antigens in the skin. The AD antigens come from molecules in the environment (extrinsic AD allergens associated with hyper IgE levels) or from self antigens (intrinsic AD autoantigens). The physiopathology of AD implies dendritic cells, specific T-cell lymphocytes, a network of type 1 and 2 cytokines and inflammatory chemokines. Extrinsic AD is the best known because of the existence of animal models and skin tests with allergens in humans (atopy patch tests), which reproduce eczema lesions. Although the role of the penetration of pneumo-allergens, prompted by abnormalities in the skin barrier, in inducing AD flares is established, recent works suggest that other types of allergens (trophallergens) and/or proteins derived from micro-organisms may be responsible in some patients. The ongoing studies on animal models of AD will no doubt permit rapid progression in our knowledge of the mechanisms involved in the origin of the disease and the reasons for its progressive increase in frequency.

Antiinflammatory properties of cetirizine in a human contact dermatitis model. Clinical evaluation of patch tests is not hampered by antihistamines

The aim of this double-blind, placebo-controlled, randomized, cross-over pilot study was to assess the antiinflammatory properties of cetirizine. A group of 27 patients with a positive patch test to an allergen consecutively received cetirizine 10 mg o.d. or placebo during a 14-day period, respectively. At day 11 of each period, patch testing was performed with the allergen. The image analysis showed a skin reaction significantly reduced under cetirizine (p = 0.03), but the clinical recording and the standardized chromatometry did not show any difference between groups. In the cross-over analysis the results of image analysis were influenced by the period, but this effect disappeared after adjustment of the ambient temperature during the 3 days of the test. These results demonstrate that cetirizine has an impact on the inflammatory process in a clinical model of cell-mediated allergic reaction, although this effect is only detected with a very sensitive technique. They also show that it is useless to stop antihistamines before patch testing, since clinical evaluation of tests is not hampered by a potent antihistamine. Additionally this study suggests that ambient temperature has an influence on the results of tests.

[Contact dermatoses: new antigens and current events]

Contact allergology is in perpetual evolution. The cutaneous allergens are not fixed in time but they appear and die by chance of habit or fashion changes, evolution of the chemistry, the cosmetology or the allergologist campaign. It seems interesting to consider the recent data concerning classical or new allergens.

Relationship between cystic duct diameter and the presence of cholelithiasis

We sought to measure cystic duct diameter in patients without biliary calculi and in those with cholelithiasis or choledocholithiasis. Using endoscopic retrograde cholangiopancreatography (ERCP), we visualized the cystic duct in 168 patients referred to our unit. These patients were distributed into three groups based on findings at ERCP: Group I (N = 57), no calculi in the gallbladder or common bile duct; group II (N = 27), stones found in the gallbladder but absent from the common bile duct; and group III (N = 34), stones present in the common bile duct with or without gallbladder stones. The diameter of the cystic duct was measured at its widest and narrowest dimensions. The largest diameter measured was greater in group III (7.72 +/- 2.29 mm) than in groups I (2.63 +/- 0.67 mm) and II (4.59 +/- 1.13 mm) (P < 0.001). The same differences were found in measurement of the smallest diameter (5.00 +/- 0.99 mm, 3.10 +/- 0.62 mm, and 1.83 +/- 0.53 mm, for groups III, II, and I, respectively) (P < 0.001). Maximal and minimal cystic duct diameter show a progressive increase at each level of disease. This increase in cystic duct size may facilitate the migration of gallstone fragments after lithotripsy and facilitate the instrumentation of the cystic duct during ERCP and laparoscopic cholecystectomy.

Patch test reactions to mite antigens: a GERDA multicentre study. Groupe d'Etudes et de Recherches en Dermato-Allergie

We performed patch tests with Dermatophagoides pteronyssinus (Dp) antigens from 2 different sources in 355 non-randomly selected patients with atopic dermatitis (AD) and 398 subjects of a control group. The study demonstrated that contact sensitization to mites occurred in an appreciable % of AD cases (20.8%), using commonly available assay products. The differences recorded between the 2 materials tested were related to the concentration of P1 antigen. Non-atopic patients rarely showed positive reactions to Dp (0.75%), when strict criteria for readings were applied and if 2 readings were performed. Patients with positive patch tests did not necessarily show positive immediate skin tests. It would be useful to carry out tests systematically in atopic patients, even if it is not yet known what modern treatment would be best for the patient. Laboratories still do not provide standardized house dust mite preparations--measuring and codifying their biological activity--for use in patch tests. It is to be hoped that the extension of this type of test will lead to the production of better test materials, in syringes with homogeneous dispersion and concentration.

Occupational dermatitis in the aircraft industry: 35 years of progress

A comparison of the occupational dermatitis occurring in the same aircraft factory during 2 separate decades, 1955-1965 and 1981-1990, is presented. Subungual pulpitis is highly specific to this industry, because of the handling of resins and sealing agents. The number of cases dropped from 122 to 40, in accordance with progress in preventive medicine and technological changes in the factory. Irritant contact dermatitis nevertheless remained appreciable, while allergic contact dermatitis greatly decreased.

Sensitization to aluminium by aluminium-precipitated dust and pollen extracts

We report 2 cases of aluminium sensitivity in adults. Each time, the means of sensitization was the inoculation of aluminium-precipitated pollen or dust extracts for hyposensitization. We conclude that aluminium allergy is not exceptional and that in these cases one can observe allergic reactions to the Finn Chamber tests.

[The Langerhans cell. Recent immunologic achievements]

The epidermal Langerhans cells has been keeping, most of its secrets for about a hundred years since its first description in 1868. Its characterization in electron microscopy by Birbeck and then the use of histoenzymology (ATPase) and monoclonal antibodies (against HLA-DR, T6, LCA, C3b...) brought a new great interest on its study. The Langerhans cell must play an important immunologic role in the epidermis because of its responsibility in the antigenic information of the lymphocytes; in this way it may represent the specific epidermal differentiation of the monocyte-macrophage cell type, which are all bone-marrow derived cells. The epidermal Langerhans cell is one of the most important links in the elicitation of contact dermatitis. Recent trends about its metabolism, antigens and functions are reviewed and discussed.