MURINE LOCAL LYMPH-NODE ASSAY FOR PREDICTIVE TESTING OF ALLERGENICITY- 2 IRRITANTS CAUSED SIGNIFICANT PROLIFERATION

Tbe murine local lymph node assay is a method for predictive testing o f contact allergenicity, but its ability to discriminate between aller gens and irritants has been questioned. To explain some of the conflic ting results with irritants, the proliferation induced by methyl salic ylate and nonanoic acid, both considered to be non-sensitisers, was fu rther investigated. Both substances showed a dose - response relations hip and clearly positive results when tested at higher concentrations (greater than or equal to 50%) and would thus be classified as potenti al sensitisers according to the present criteria for a positive assay result. In the case of methyl salicylate, the use of either dimethyl f ormamide or methyl ethyl ketone as vehicle did not significantly influ ence the results. The negative results obtained for methyl salicylate in some earlier reports were probably due to testing at too low concen trations. The proliferation induced by irritants such as methyl salicy late and nonanoic acid and inter alia sodium dodecyl sulfate, Triton X -100, oxalic acid, chloroform/methanol (2:1) must be better recognized and elucidated before the assay can be generally accepted as a predic tive test method.