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Li W, Li P, Fang Y, Lei TC, Dong K, Zou J, Gong W, Xie S, Huang Z. Quantitative assessment of skin swelling using optical coherence tomography. Photodiagnosis Photodyn Ther 2019; 26:413-419. [DOI: 10.1016/j.pdpdt.2019.04.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/29/2019] [Accepted: 04/29/2019] [Indexed: 10/26/2022]
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Turnock S, Gerbeix C, Thirion-Delalande C, Pearson N, Forster R. Assessment of phototoxicity in pigmented Long-Evans rat: sparfloxacin and 8-methoxypsoralen. Regul Toxicol Pharmacol 2017; 92:303-314. [PMID: 29196029 DOI: 10.1016/j.yrtph.2017.11.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 11/20/2017] [Accepted: 11/27/2017] [Indexed: 10/18/2022]
Abstract
The aim of the present work was to evaluate the effects of photo-activated toxicity induced after administration of two known melanin-binding phototoxic compounds, sparfloxacin (SPX) and 8-methoxypsoralen (8-MOP), followed or not by UVA/Vis exposure, in pigmented rats (Long Evans: LE) and albino rats (Sprague Dawley: SD). Groups of three rats were treated with SPX or 8-MOP by oral gavage for six consecutive days. Irradiated animals were submitted to a UVA/Vis light dose standardized to 10 J/cm2 UVA daily. Clinical signs, cutaneous reactions and body weight were monitored throughout the study period. Ear biopsy weight, lymph node weight and lymph node cell count were determined at necropsy. Ophthalmologic examinations were performed before the first treatment and on the day of sacrifice. Microscopic examinations were performed on skin biopsies and eyes. Phototoxicity was demonstrated for both SPX and 8-MOP in the pigmented and albino strains, in terms of auricular irritation, lymph node weight and proliferation index, cutaneous reactions and ocular histopathology. LE rats were less sensitive than SD rats, especially at the ocular level, supporting the notion that pigmentation may provide protection against photo-activation. The pigmented rat may be a more relevant model than the albino rat for human safety evaluation.
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Affiliation(s)
- Stephen Turnock
- CiToxLAB France, 27005 Evreux, France; Kings College London, London, UK
| | | | | | - Nick Pearson
- CiToxLAB France, 27005 Evreux, France; Pharmaceutical Sciences, pRED, Roche Innovation Center Basel, Switzerland
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Schümann J, Boudon S, Ulrich P, Loll N, Garcia D, Schaffner R, Streich J, Kittel B, Bauer D. Integrated Preclinical Photosafety Testing Strategy for Systemically Applied Pharmaceuticals. Toxicol Sci 2014; 139:245-56. [DOI: 10.1093/toxsci/kfu026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Boudon SM, Plappert-Helbig U, Odermatt A, Bauer D. Characterization of vemurafenib phototoxicity in a mouse model. Toxicol Sci 2013; 137:259-67. [PMID: 24154489 DOI: 10.1093/toxsci/kft237] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vemurafenib is a first-in-class, small molecule B-Raf kinase inhibitor for the treatment of patients with unresectable or metastatic melanoma carrying the BRAFV600E mutation, commercially available since 2011. A general phototoxic potential was identified early during development; however, based on results of an animal study in hairless rats, it was concluded that there would exist no relevant risk for humans. Surprisingly, signs of clinical photosensitivity were reported in many patients during clinical development. Therefore, it became a fundamental question to understand this discrepancy. An established mouse model (oral UV-Local Lymph Node Assay, UV-LLNA) for the assessment of in vivo photosafety was used to investigate the impact of formulations, dose levels, duration of treatment, and timing of irradiation. Moreover, a basic pharmacokinetic profile was established within the same mouse strain. We were able to demonstrate dose- and time-dependent phototoxicity of vemurafenib using commercially available tablets (stabilized amorphous material). The lowest phototoxic dose was 350 mg/kg administrated for 3 consecutive days followed by exposure to UV-visible irradiation at a UVA-normalized dose of 10 J/cm². In comparison, pure vemurafenib, which easily forms crystalline variants and is known to have poor bioavailability, was tested at 350 mg/kg, and no signs of phototoxicity could be seen. The most apparent difference between the early study in hairless rats and this study in mice was the spectral range of the irradiation light source (350-400 nm vs 320-700 nm). Because vemurafenib does not absorb sufficiently light above 350 nm, this difference can easily explain the negative earlier study result in hairless rats.
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Affiliation(s)
- Stéphanie Marie Boudon
- * Preclinical Safety, Novartis Institutes of BioMedical Research, 4002 Basel, Switzerland
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Establishment of an in vitro photoassay using THP-1 cells and IL-8 to discriminate photoirritants from photoallergens. Toxicol In Vitro 2013; 27:1920-7. [DOI: 10.1016/j.tiv.2013.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 06/07/2013] [Accepted: 06/24/2013] [Indexed: 11/22/2022]
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Basketter D, Crozier J, Hubesch B, Manou I, Mehling A, Scheel J. Optimised testing strategies for skin sensitization – The LLNA and beyond. Regul Toxicol Pharmacol 2012; 64:9-16. [DOI: 10.1016/j.yrtph.2012.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/01/2012] [Accepted: 06/04/2012] [Indexed: 11/28/2022]
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Ceridono M, Tellner P, Bauer D, Barroso J, Alépée N, Corvi R, De Smedt A, Fellows MD, Gibbs NK, Heisler E, Jacobs A, Jirova D, Jones D, Kandárová H, Kasper P, Akunda JK, Krul C, Learn D, Liebsch M, Lynch AM, Muster W, Nakamura K, Nash JF, Pfannenbecker U, Phillips G, Robles C, Rogiers V, Van De Water F, Liminga UW, Vohr HW, Wattrelos O, Woods J, Zuang V, Kreysa J, Wilcox P. The 3T3 neutral red uptake phototoxicity test: Practical experience and implications for phototoxicity testing – The report of an ECVAM–EFPIA workshop. Regul Toxicol Pharmacol 2012; 63:480-8. [PMID: 22687423 DOI: 10.1016/j.yrtph.2012.06.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
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Assessment of the sensitizing potential of textile disperse dyes and some of their metabolites by the loose-fit coculture-based sensitization assay (LCSA). Arch Toxicol 2012; 86:733-40. [DOI: 10.1007/s00204-012-0811-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 01/31/2012] [Indexed: 10/28/2022]
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Peukert S, Nunez J, He F, Dai M, Yusuff N, DiPesa A, Miller-Moslin K, Karki R, Lagu B, Harwell C, Zhang Y, Bauer D, Kelleher JF, Egan W. A method for estimating the risk of drug-induced phototoxicity and its application to smoothened inhibitors. MEDCHEMCOMM 2011. [DOI: 10.1039/c1md00144b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kimber I, Basketter DA, Gerberick GF, Ryan CA, Dearman RJ. Chemical allergy: translating biology into hazard characterization. Toxicol Sci 2010; 120 Suppl 1:S238-68. [PMID: 21097995 DOI: 10.1093/toxsci/kfq346] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The induction by chemicals of allergic sensitization and allergic disease is an important and challenging branch of toxicology. Skin sensitization resulting in allergic contact dermatitis represents the most common manifestation of immunotoxicity in humans, and many hundreds of chemicals have been implicated as skin sensitizers. There are far fewer chemicals that have been shown to cause sensitization of the respiratory tract and asthma, but the issue is no less important because hazard identification remains a significant challenge, and occupational asthma can be fatal. In all areas of chemical allergy, there have been, and remain still, intriguing challenges where progress has required a close and productive alignment between immunology, toxicology, and clinical medicine. What the authors have sought to do here is to exemplify, within the framework of chemical allergy, how an investment in fundamental research and an improved understanding of relevant biological and biochemical mechanisms can pay important dividends in driving new innovations in hazard identification, hazard characterization, and risk assessment. Here we will consider in turn three specific areas of research in chemical allergy: (1) the role of epidermal Langerhans cells in the development of skin sensitization, (2) T lymphocytes and skin sensitization, and (3) sensitization of the respiratory tract. In each area, the aim is to identify what has been achieved and how that progress has impacted on the development of new approaches to toxicological evaluation. Success has been patchy, and there is still much to be achieved, but the journey has been fascinating and there have been some very important developments. The conclusion drawn is that continued investment in research, if coupled with an appetite for translating the fruits of that research into imaginative new tools for toxicology, should continue to better equip us for tackling the important challenges that remain to be addressed.
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Affiliation(s)
- Ian Kimber
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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Ahuja V, Platzek T, Fink H, Sonnenburg A, Stahlmann R. Study of the sensitising potential of various textile dyes using a biphasic murine local lymph node assay. Arch Toxicol 2010; 84:709-18. [DOI: 10.1007/s00204-010-0566-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2010] [Accepted: 06/09/2010] [Indexed: 11/29/2022]
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Appraisal of the sensitising potential of orally and dermally administered Mercaptobenzothiazol by a biphasic protocol of the local lymph node assay. Arch Toxicol 2009; 83:933-9. [DOI: 10.1007/s00204-009-0426-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 03/24/2009] [Indexed: 10/20/2022]
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Investigation of the sensitising and cross-sensitising potential of textile dyes and β-lactam antibiotics using a biphasic mice local lymph node assay. Arch Toxicol 2009; 83:691-9. [DOI: 10.1007/s00204-009-0407-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 01/15/2009] [Indexed: 10/21/2022]
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Local lymph node assay (LLNA): comparison of different protocols by testing skin-sensitizing epoxy resin system components. Regul Toxicol Pharmacol 2008; 52:290-8. [PMID: 18824053 DOI: 10.1016/j.yrtph.2008.08.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 08/08/2008] [Accepted: 08/27/2008] [Indexed: 11/22/2022]
Abstract
Thirteen epoxy resin system components were tested in the LLNA with regard to their sensitizing potency. Lymph node stimulation was quantified not only by measuring the incorporation of [3H]-thymidine into the ear lymph nodes but also the counts of cells recovered from these organs. Equivalent figures were obtained with both endpoints used for the evaluation of lymph node cell proliferation if the reference stimulation indices were adjusted. When dissolved in acetone, all test substances showed skin-sensitizing potential, mainly on the boundary between "strong" and "moderate" according to common potency evaluation schemes. Replacing acetone with acetone/olive oil (4:1) as a vehicle for four selected test items, resulted in considerably lower estimated concentrations for sensitization induction. The challenges in comparing the results obtained by different LLNA variations are discussed.
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Idehara K, Yamagishi G, Yamashita K, Ito M. Characterization and evaluation of a modified local lymph node assay using ATP content as a non-radio isotopic endpoint. J Pharmacol Toxicol Methods 2008; 58:1-10. [PMID: 18462956 DOI: 10.1016/j.vascn.2008.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2007] [Accepted: 03/18/2008] [Indexed: 11/29/2022]
Abstract
INTRODUCTION The murine local lymph node assay (LLNA) is an accepted and widely used method for assessing the skin-sensitizing potential of chemicals. Here, we describe a non-radio isotopic modified LLNA in which adenosine triphosphate (ATP) content is used as an endpoint instead of radioisotope (RI); the method is termed LLNA modified by Daicel based on ATP content (LLNA-DA). METHODS Groups of female CBA/JNCrlj mice were treated topically on the dorsum of both ears with test chemicals or a vehicle control on days 1, 2, and 3; an additional fourth application was conducted on day 7. Pretreatment with 1% sodium lauryl sulfate solution was performed 1 h before each application. On day 8, the amount of ATP in the draining auricular lymph nodes was measured as an alternative endpoint by the luciferin-luciferase assay in terms of bioluminescence (relative light units, RLU). A stimulation index (SI) relative to the concurrent vehicle control was derived based on the RLU value, and an SI of 3 was set as the cut-off value. RESULTS Using the LLNA-DA method, 31 chemicals were tested and the results were compared with those of other test methods. The accuracy of LLNA-DA vs LLNA, guinea pig tests, and human tests was 93% (28/30), 80% (20/25), and 79% (15/19), respectively. The estimated concentration (EC) 3 value was calculated and compared with that of the original LLNA. It was found that the EC3 values obtained by LLNA-DA were almost equal to those obtained by the original LLNA. DISCUSSION The SI value based on ATP content is similar to that of the original LLNA as a result of the modifications in the chemical treatment procedure, which contribute to improving the SI value. It is concluded that LLNA-DA is a promising non-RI alternative method for evaluating the skin-sensitizing potential of chemicals.
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Affiliation(s)
- Kenji Idehara
- Analysis Service Center, Daicel Chemical Industries, Ltd., 1239, Shinzaike, Aboshi-ku, Himeji, Hyogo 671-1283, Japan.
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Struwe M, Greulich KO, Junker U, Jean C, Zimmer D, Suter W, Plappert-Helbig U. Detection of photogenotoxicity in skin and eye in rat with the photo comet assay. Photochem Photobiol Sci 2008; 7:240-9. [DOI: 10.1039/b715756h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Suter W. Improving Decision-Making in Drug Development Using In Vitro Toxicology Screening. ACTA ACUST UNITED AC 2007. [DOI: 10.2165/00124363-200721050-00005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Stahlmann R, Wegner M, Riecke K, Kruse M, Platzek T. Sensitising potential of four textile dyes and some of their metabolites in a modified local lymph node assay. Toxicology 2006; 219:113-23. [PMID: 16388883 DOI: 10.1016/j.tox.2005.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 11/08/2005] [Accepted: 11/08/2005] [Indexed: 11/19/2022]
Abstract
We studied the sensitising and allergenic potentials of the textile dyes disperse yellow 3, disperse orange 30, disperse red 82, disperse yellow 211 and two metabolites of disperse yellow 3, 4-aminoacetanilide and 2-amino-p-cresol, using modified protocols of the murine "local lymph node assay" (LLNA). Test substances were applied either to the dorsum of the mice ears (sensitisation protocol) or they were first applied to the skin of their backs and 2 weeks later to their ears (sensitisation-challenge protocol). In addition to the endpoints weight and cell number of the draining ear lymph nodes we analysed lymphocyte subpopulations by flow cytometry. In the sensitisation protocol, disperse yellow 3 and its metabolite 4-aminoacetanilide did not induce significant effects, whereas in the sensitisation-challenge protocol cell number and lymph node weight increased significantly indicating a sensitising potential in NMRI mice. Hence, two-phase treatment (skin of the back, ear) increased the sensitivity of this assay. The second metabolite of disperse yellow 3, 2-amino-p-cresol, showed distinct effects in both treatment protocols; this applied mainly to the parameters cell number and lymph node weight. The dye disperse red 82 caused ambiguous increases in lymph node weight and cell number in the sensitisation protocol which were not reproduced in the sensitisation-challenge protocol, ruling out a relevant sensitising potential for this dye in NMRI mice. Disperse yellow 211 and disperse orange 30 did not induce relevant changes under our experimental conditions. Phenotyping of lymphocytes did not influence the assessment of these dyes.
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Affiliation(s)
- Ralf Stahlmann
- Institute of Clinical Pharmacology and Toxicology, Charité-Campus Benjamin Franklin, Garystrasse 5, 14195 Berlin, Germany.
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Ehling G, Hecht M, Heusener A, Huesler J, Gamer AO, van Loveren H, Maurer T, Riecke K, Ullmann L, Ulrich P, Vandebriel R, Vohr HW. An European inter-laboratory validation of alternative endpoints of the murine local lymph node assay: First round. Toxicology 2005; 212:60-8. [PMID: 15950356 DOI: 10.1016/j.tox.2005.04.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 04/25/2005] [Accepted: 04/25/2005] [Indexed: 11/30/2022]
Abstract
The new OECD guideline 429 (skin sensitization: local lymph node assay) is based upon a protocol, which utilises the incorporation of radioactivity into DNA as a measure for cell proliferation in vivo. The guideline also enables the use of alternative endpoints in order to assess draining lymph node (LN) cell proliferation. Here we describe the first round of an inter-laboratory validation of alternative endpoints in the LLNA conducted in seven laboratories. The validation study was managed and supervised by the Swiss Agency for Therapeutic Products, Swissmedic. Statistical analyses of all data were performed by an independent centre at the University of Bern, Department of Statistics. Ear-draining, LN weight and cell count were used to assess proliferation instead of radioactive labeling of lymph node cells. In addition, the acute inflammatory skin reaction was measured by ear swelling and weight of circular biopsies of the ears to identify skin irritating properties of the test items. Hexylcinnamaldehyde (HCA) and three blinded test items were applied to female, 8--10 weeks old NMRI and BALB/c mice. Results were sent via the independent study coordinator to the statistician. The results of this first round showed that the alternative endpoints of the LLNA are sensitive and robust parameters. The use of ear weights added an important parameter assessing the skin irritation potential, which supports the differentiation of pure irritative from contact allergenic potential. There were absolute no discrepancies between the categorisation of the three test substances A--C determined by each single participating laboratories. The results highlighted also that many parameters do have an impact on the strength of the responses. Therefore, such parameters have to be taken into consideration for the categorisation of compounds due to their relative sensitizing potencies.
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Affiliation(s)
- G Ehling
- Aventis Pharma Deutschland GmbH, ProTox, D-65795 Hattersheim, Germany
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Ehling G, Hecht M, Heusener A, Huesler J, Gamer AO, van Loveren H, Maurer T, Riecke K, Ullmann L, Ulrich P, Vandebriel R, Vohr HW. An European inter-laboratory validation of alternative endpoints of the murine local lymph node assay. Toxicology 2005; 212:69-79. [PMID: 15878228 DOI: 10.1016/j.tox.2004.12.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Accepted: 12/30/2004] [Indexed: 11/29/2022]
Abstract
The original local lymph node assay (LLNA) is based on the use of radioactive labelling to measure cell proliferation. Other endpoints for the assessment of proliferation are also authorized by the OECD Guideline 429 provided there is appropriate scientific support, including full citations and description of the methodology (OECD, 2002. OECD Guideline for the Testing of Chemicals; Skin Sensitization: Local Lymph Node Assay, Guideline 429. Paris, adopted 24th April 2002.). Here, we describe the outcome of the second round of an inter-laboratory validation of alternative endpoints in the LLNA conducted in nine laboratories in Europe. The validation study was managed and supervised by the Swiss Agency for Therapeutic Products (Swissmedic) in Bern. Ear-draining lymph node (LN) weight and cell counts were used to assess LN cell proliferation instead of [3H]TdR incorporation. In addition, the acute inflammatory skin reaction was measured by ear weight determination of circular biopsies of the ears to identify skin irritation properties of the test items. The statistical analysis was performed in the department of statistics at the university of Bern. Similar to the EC(3) values defined for the radioactive method, threshold values were calculated for the endpoints measured in this modification of the LLNA. It was concluded that all parameters measured have to be taken into consideration for the categorisation of compounds due to their sensitising potencies. Therefore, an assessment scheme has been developed which turned out to be of great importance to consistently assess sensitisation versus irritancy based on the data of the different parameters. In contrast to the radioactive method, irritants have been picked up by all the laboratories applying this assessment scheme.
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Affiliation(s)
- G Ehling
- Aventis Pharma Deutschland GmbH, ProTox, D-65795 Hattersheim, Germany
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Hans-Werner V, Jürgen AH. The local lymph node assay being too sensitive? Arch Toxicol 2005; 79:721-8. [PMID: 16025312 DOI: 10.1007/s00204-005-0005-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Accepted: 05/18/2005] [Indexed: 10/25/2022]
Abstract
The local lymph node assay (LLNA) and modifications thereof were recently recognized by the OECD as stand-alone methods for the detection of skin-sensitizing potential. However, although the validity of the LLNA was acknowledged by the ICCVAM, attention was drawn to one major problem, i.e., the possibility of false positive results caused by non-specific cell activation as a result of inflammatory processes in the skin (irritation). This is based on the fact that inflammatory processes in the skin may lead to non-specific activation of dendritic cells, cell migration and non-specific proliferation of lymph node cells. Measuring cell proliferation by radioactive or non-radioactive methods, without taking the irritating properties of test items into account, leads thus to false positive reactions. In this paper, we have compared both endpoints: (1) cell proliferation alone and (2) cell proliferation in combination with inflammatory (irritating) processes. It turned out that a considerable number of tests were "false positive" to the definition mentioned above. By excluding such false positive results the LLNA seems not to be more sensitive than relevant guinea pig assays. These various methods and results are described here.
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Affiliation(s)
- Vohr Hans-Werner
- Toxicology, Bayer HealthCare AG, Aprather Weg, 42096 Wuppertal, Germany.
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Straube F, Grenet O, Bruegger P, Ulrich P. Contact allergens and irritants show discrete differences in the activation of human monocyte-derived dendritic cells: consequences for in vitro detection of contact allergens. Arch Toxicol 2004; 79:37-46. [PMID: 15372140 DOI: 10.1007/s00204-004-0606-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Accepted: 08/10/2004] [Indexed: 10/26/2022]
Abstract
In recent years test systems have been described that may be applied routinely to discriminate between contact allergens and irritants in vitro. Using human monocyte-derived dendritic cells (MoDC), this study was designed to refine the settings of a potential routine screening protocol for contact allergens and to investigate the so far poorly defined concentration dependency of contact allergen-specific effects. MoDC were generated by 6 days of culture in the presence of IL-4 and GM-CSF and were then cultured for 24 or 48 h in medium with lipopolysaccharide (LPS), contact allergens [picrylsulphonic acid (TNBS), 1-chloro-2,4-dinitrobenzene (DNCB)] or irritants [sodium dodecyl sulphate (SDS), benzalkonium chloride (BAC)] that were free of detectable endotoxin contamination. The induction of CD86 and HLA-DR expression was quantified by flow cytometry as markers for MoDC activation. LPS activation upregulated CD86 about 20-fold and HLA-DR expression about 4-fold. Compared to LPS, contact allergens had weaker effects. TNBS and DNCB induced activation marker upregulation starting slightly below the cytotoxic concentration and increasing in a dose-dependent manner. However, at partially cytotoxic concentrations, irritants also induced CD86 and HLA-DR expression, as confirmed by flow cytometry and quantitative RT-PCR. Both SDS and BAC induced activation marker expression on surviving MoDC, when more than 50% of the MoDC population had been killed by the treatment. Consequently, routine testing of unknown substances would need to quantify activation marker expression as well as cytotoxicity in parallel. In the concentration range around the lowest cytotoxic concentration, the assay may be able to discriminate between contact allergens and irritants.
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Kimber I, Dearman RJ, Basketter DA, Ryan CA, Gerberick GF. The local lymph node assay: past, present and future. Contact Dermatitis 2002; 47:315-28. [PMID: 12581276 DOI: 10.1034/j.1600-0536.2002.470601.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The local lymph node assay (LLNA) was developed originally as a method for the identification of chemicals that have the potential to cause skin sensitization and allergic contact dermatitis. The assay is based on an understanding that the acquisition of contact sensitization is associated with, and dependent upon, the stimulation by chemical allergens of lymphocyte proliferative responses in skin-draining lymph nodes. Those chemicals that provoke a defined level of lymph node cell (LNC) proliferation (a 3-fold or greater increase compared with concurrent vehicle controls) are classified as skin sensitizers. Following its original inception and development, the LLNA was the subject of both national and international interlaboratory collaborative trials, and of very detailed comparisons with other test methods and with human skin sensitization data. The assay has now been validated fully as a stand-alone test for the purposes of hazard identification. In recent years, there has been a growing interest also in the use of the LLNA to assess the potency of contact allergens and in risk assessment. There is reason to believe that the extent of skin sensitization achieved is associated with the vigour of LNC proliferation induced in draining nodes. Given this relationship, the relative potency of skin sensitizing chemicals is measured in the LLNA by derivation of an EC3 value, this being the concentration of chemical required to provoke a 3-fold increase in the proliferation of LNC compared with controls. Experience to date indicates that relative potency as determined using this approach correlates closely with what is known of the activity of skin sensitizing chemicals in humans. In this article, we review the development, evaluation and validation of the LLNA for the purposes of hazard identification, and the more recent application of the method for evaluation of potency in the context of risk assessment. In addition, we consider what new applications and modifications are currently being investigated.
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Affiliation(s)
- Ian Kimber
- Syngenta Central Toxicology Laboratory, Alderley Park, Macclesfield, Cheshire, UK.
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