We recently presented a modified local lymph node test which made it possible to quickly and reliably differentiate between irritative and allergic skin reactions with extremely simple parameters. The Integrated Model for the Differentiation of Skin Reactions (IMDS) test combines measurement of cell proliferation in draining lymph nodes with measurement of primary ear swelling after topical application of the test substance on three consecutive days. In contrast to the 'classic' skin sensitisation test in guinea-pigs the IMDS test is considerably faster and is based on objective measured data, not subjective skin evaluations. Like the Local Lymph Node Assay (LLNA), measurement of allergic potential in the IMDS test is based on the underlying immunological mechanisms, but also considers the behaviour of immune competent cells following non-specific activation by irritants. In addition, the IMDS test can employ UV radiation after application of the substance and, therefore, make differentiation possible between different types of skin photoreaction (photoallergy and photoirritation) after both topical and systemic administration. Attempts to achieve this kind of discrimination with the LLNA necessitate considerably greater expenditure, as proliferation in the draining lymph nodes can also be induced by moderate to extreme (photo)irritants. In a previous paper in which we presented the IMDS test, we examined each type of reaction in reference to one single standard; the next logical step was therefore a broad-based intra-laboratory validation. An important factor in the validation was the use of standards that had been thoroughly examined in both guinea pig and mouse systems and were also relevant with regard to estimation of the risk for humans. The data presented here show that the IMDS is a simple and reliable tool for obtaining fast and reproducible assessments of potential (photo)allergic and (photo)irritant skin reactions to substances.
Objective-The autoantigen p68 is a target of autoantibodies as well as autoreactive T cells with a high specificity in rheumatoid arthritis (RA). The binding characteristics of the autoantibodies to their antigen were now analysed biochemically and cytologically. Methods-Deglycosylation techniques as well as lectin and sugar competition experiments were performed to p68 to discover if the antibodies detected a glycoepitope. Its antigenicity was investigated applying anti-p68 antibodies derived from RA patients in comparison with polyclonal rabbit anti-p68 antibodies. Results-p68 specific antibodies from RA patients did not to bind to p68 that had been deglycosylated by alkaline -elimination, O-glycosidase or periodate treatment. In contrast, binding of p68 specific antibodies raised in rabbit was unaVected by either deglycosylation protocol. Furthermore, lectins specific for the carbohydrate N-acetylglucosamine competed with p68 specific antibodies from RA patients for antigen binding. N-acetylglucosamine by itself also competed with patient derived anti-p68 antibodies for p68 binding. Again, rabbit anti-p68 antibodies did not elicit these competitive eVects. Applying cytoimmunofluorescence, p68 was present in the cytoplasm or endoplasmic reticulum and also in low abundance on the cell surface. Under heatshock conditions, p68 was detectable in the nucleus. Conclusions-Autoimmunity to p68 during RA is carried by anti-carbohydrate autoantibodies. The carbohydrate modification of p68 appears to be N-acetylglucosamine, which may reflect the regulation of intracellular localisation of the antigen. It is hypothesised that a shift in glycosylation pattern accompanied by an unphysiological localisation of the antigen could trigger antigenicity of p68 during the pathogenesis of RA.
The elicitation of respiratory allergy in animal models is exquisitely complex and interpretation of results from different laboratories cannot readily be compared due to variability in testing protocols, biomarkers and techniques used to identify 'positive' responses. On the one hand, guinea-pigs have been proposed as a good model with which to study allergic and irritant bronchial hyperresponsiveness. On the other hand, considerable efforts have been made to develop animal models that take the immunological mechanisms into account to reduce the complexity as well as duration of the guinea-pig assays. In principle, local skin reactions can easily be determined by the local lymph node assay (LLNA) introduced by Kimber and Weisenberger. In contrast to lung sensitization there are already simplified and reliable models available to test for and discriminate contact sensitizers from skin irritants, i.e. the modified local lymph node assay IMDS (integrated model for the differentiation of skin reactions). Modifications of this assay verified that methods other than radioactive labelling may be comparably sensitive, and that it is possible to eliminate 'false positive' results induced by irritants (IMDS). Thus, we asked whether there could be a similar simplified model like the modified LLNA or IMDS for investigations of respiratory allergens. Therefore, we analysed immune reactions induced by the dermal and respiratory route, respectively. Analyses of the draining lymph nodes of the lung and the ear were carried out before and after challenge via the pulmonary tract. The results clearly support that (1) the reactions in the lung draining lymph nodes could be used as early indicators of respiratory sensitization, and (2) the specificity of the immune competent cells seem to be dependent of the route of administration during induction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.