LYMPH-NODE CELL-PROLIFERATION ASSAY IN GUINEA-PIGS FOR THE ASSESSMENTOF SENSITIZING POTENTIALS OF CHEMICAL-COMPOUNDS

The efficacy of a lymph node cell proliferation assay in the guinea pi g as a first stage screening method of predicting sensitizing potentia ls of chemicals was studied by using several haptens. Animals were sen sitized by a single 24-hr occlusive patch (24 cp), intradermal injecti on (id) and a combination of id and 24 cp, at a concentration used for guinea pig conventional contact hypersensitivity assay methods. Contr ol animals were treated with vehicle(s) only. Suspensions of the lymph node cells (LNC) were individually prepared and cultured with [H-3]me thyl thymidine ([H-3]TdR). [H-3]TdR incorporation was measured and a s timulation index (SI) was calculated as a ratio of the mean [H-3]TdR i ncorporation in sensitized animals and the mean [H-3]TdR incorporation in control animals. LNC sensitized by 24 cp with 2,4-dinitrochloroben zene proliferated maximally and significantly at day 5, whereas this o ccurred at day 7 after id sensitization. Significant LNC proliferation and high SI values were obtained successively by a combination of 24 cp and id. Moreover, strongly sensitizing chemicals increased signific ant LNC proliferation (SI > 2.0); weakly to moderately sensitizing che micals also induced significant LNC proliferation (SI = 1.3-1.7). On t he other hand, a primary irritant, sodium dodecyl sulfate, failed to e ncourage LNC proliferation (S approximate to 1.0).