MORPHOLOGY OF POPLITEAL LYMPH-NODE RESPONSES IN BROWN-NORWAY RATS

The popliteal lymph node (PLN) assay has been proposed as a tool to pr edict in rodents those xenobiotics likely to induce autoimmune reactio ns in humans. To further validate this assay and to study the mechanis ms involved, histologic changes in PLNs from rats injected with strept ozotocin, diphenylhydantoin, pure acetone, or 50% ethanol were compare d to a local graft-versus-host (GvH) reaction. This study suggests tha t routine histology of PLNs is instrumental to discard primary irritan ts. In addition, the hypothesis of a GvH-like mechanism in positive PL N responses is supported by the finding that the reference compounds s treptozotocin and diphenylhydantoin produced histologic changes simila r to a ''true'' local GvH reaction.