Local lymph node assay: use in hazard and risk assessment

Abstract

The murine local lymph node assay (LLNA) was developed as an alternative method for the identification of chemicals that have the ability to cause skin sensitization and allergic contact dermatitis. The assay now has been evaluated extensively in the context of both national and international inter‐laboratory collaborative trials and has been the subject of detailed comparisons with guinea pig test methods and human skin sensitization data. On the basis of these evaluations the LLNA has been endorsed recently by the US Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) as a stand‐alone method for skin sensitization testing. The assay offers a number of important benefits compared with conventional guinea pig test methods, among these being provision of an objective and quantitative endpoint. Moreover, the LLNA provides advantages in the context of animal welfare; compared with guinea pig tests, fewer animals are required and these animals are subject to less trauma. It is important now that the validation status of the LLNA is recognized and the method applied widely so that these advantages may be realized. Hazard identification represents only the first step in the risk assessment process. A full toxicological evaluation of skin sensitization activity requires an understanding of relative potency. Guinea pig methods do not lend themselves readily to assessment of potency, and interest recently has focused on the utility of the LLNA for this purpose. Contained within this review article are brief descriptions of the history of the LLNA and the immunobiological basis for the method, together with detailed accounts of the conduct and interpretation of the assay. Procedural modifications to, and alternative endpoints for, the LLNA are considered also. Finally, the current regulatory status of the LLNA is summarized and the application of the method for the purposes of defining relative potency and developing risk assessments is reviewed. Copyright © 1999 John Wiley & Sons, Ltd.

Sensitizing Potential of Chromated Copper Arsenate in Local Lymph Node Assays Differs with the Solvent Used

“…The LLNA was developed initially for hazard identification (Kimber and Basketter, 1992;Basketter et al, 1996Dearman et al, 1999;Kimber et al, 2003) and has now been evaluated extensively and validated formally (Kimber and Basketter, 1992;Dearman et al, 1999;Gerberick et al, 2000;Basketter et al, 2002;Kimber et al, 2003).…”

10.1538/expanim.63.435

“…According to the standard criterion for a positive response (SI ≥3; Dearman et al . [ 9 ]), GA at 0.5% was confirmed to be a sensitizing agent.…”

“…We first confirmed the concentration of GA that yielded a positive response (i.e., EC3 value ≥3) in the LLNA. This test assesses the potential of chemicals to cause a primary T-lymphocyte proliferative response after topical application of the test chemical to the skin of mice [ 9 ]. Because the LLNA involves dermal application, strictly speaking, it is appropriate only for assessing the risk of allergic contact dermatitis.…”

Evaluation of 4-methylcyclohexanemethanol (MCHM) in a combined irritancy and Local Lymph Node Assay (LLNA) in mice

“…Although the magnitude of proliferation in the draining lymph node cells closely correlates with chemical sensitization it has been reported that irritants can induce proliferation in the draining lymph nodes, and, if potent enough, induce false positives in the LLNA (ICCVAM, 2009; Gerberick et al, 2001; Dearman et al, 1999). Since crude MCHM produced both a positive skin irritancy and sensitization response, there is some concern that the LLNA response is providing a false signal.…”