The Role of the Inflammatory Response of Skin and Lymph Nodes in the Induction of Sensitization to Simple Chemicals

Simple chemicals which were sensitizers when applied to the skin of guinea pigs or injected in complete Freund's adjuvant (CFA) possessed primary irritant properties. Chemicals which were sensitizers when injected in CFA but nonsensitizers when applied to the skin had no primary irritancy. Treatment of guinea pig skin with certain inflammatory agents before skin application of chemicals from this latter group was associated with the development of contact sensitivity. While all three inflammatory agents examined induced a nonspecific inflammatory cell infiltrate, only two promoted the development of sensitivity. The two chemicals which were nonsensitizers when applied to the skin but sensitizers when injected in CFA caused expansion of the paracortical areas of the draining lymph nodes and the development of pyroninophilic blast cells in this region. It is suggested that the inflammatory properties of simple chemicals, whether inherent in the chemical or exogenous, can influence sensitization.