Effect of cyclophosphamide on the cellular infiltrate in experimental allergic contact dermatitis

The influence of cyclophosphamide on contact allergy was studied by a method based on the count of cells infiltrating epicutaneous test sites in sensitized guinea pigs. Cyclophosphamide was injected 72 h before sensitization with dinitrochlorobenzene (DNCB). On testing 2 weeks later, marked mononuclear cell infiltration and dramatic increase in the count of basophil polymorphonuclear cells in the upper corium were found, compared to the control group. Cell infiltration in tests performed 1 and 3 weeks after sensitization differed from the reaction after 2 weeks. When cyclophosphamide was given 72 h before testing done 2 weeks after sensitization, both mononuclear and polymorphonuclear counts were found to be greatly reduced. This in vivo method of assessing the degree and composition of cellular infiltration in a contact allergic reaction after different periods of time throws new light on the influence of drugs on a cell-mediated immune response and also the variation in response with time.