Measurement and differentiation of the cellular infiltrate in expermiental allergic contact dermatitis.

We describe a quantitative method for the grading of contact allergic reactions in guinea pigs. These reactions are characterized by marked cellular infiltration, and the method is based on total and differential counting of cells in the upper corium. A varying and objectively gradable increase in mononuclear and basophil polymorphonuclear cells was found. In naked-eye-positive reactions this increase was highly significant 24, 48, and 72 hours after epicutaneous application of dinitrochlorobenzene (DNCB). The degree of cellular infiltration reflects aspects of a cell-mediated immune response other than the visible reaction ordinarily made use of. The method can be used to study how systemically or topically administered drugs affect cellular features in contact allergy.