Draining lymph node cell activation in guinea pigs: Comparisons with the murine local lymph node assay

Abstract

The local lymph node assay in the mouse is a novel predictive test for the identification of contact sensitizing chemicals. The purpose of the studies described was to determine whether a similar local lymph node assay could be performed successfully in guinea pigs: currently the species of choice for assessment of sensitizing potential for regulatory purposes. Ten sensitizing chemicals (oxazolone, picryl chloride, 2,4-dinitrofluorobenzene, benzocaine, cinnamic aldehyde, 2,4-dinitrothiocyanobenzene, p-nitrosodimethylaniline, formaldehyde, p-phenylenediamine and cyanuric chloride) and equal concentrations of sodium lauryl sulphate were examined in a guinea pig local lymph node assay. Animals received three consecutive daily applications of various concentrations of the test chemical on the dorsum of both ears. Control animals were untreated. Five days following the initiation of exposure, draining auricular lymph nodes were excised and weighed. Suspensions of lymph node cells (LNC) were prepared and cultured for 24 or 48 h and proliferation measured by incorporation of [ 3H]thymidine. Exposure to at least one concentration of all sensitizing chemicals, other than benzocaine, induced proliferation by draining LNC. Responses were higher at 24 h rather than 48 h. Evidence is presented that guinea pig LNC proliferation may be enhanced or maintained by addition to culture of an exogenous source of the T cell growth factor interleukin 2 (IL-2). Draining lymph node weight was increased following exposure to some sensitizing chemicals but, compared with LNC proliferation, provided a less sensitive correlate of lymph node activation. Exposure to sodium lauryl sulphate failed to induce changes in either lymph node weight or LNC proliferation. Data are compared with three-day murine local lymph node assays performed concurrently. The available information indicates that the local lymph node assay may be performed in guinea pigs.