Comparison of DNFB and K2Cr2O7 'flare-up' reactions in the guinea pig

A comparison has been made of the 'flare-up' of 2,4-dinitrofluorobenzene (DNFB) contact reactions with that of 'flare-up' of potassium dichromate (K2Cr2O7) contact sensitivity reactions following the intravenous injection of dinitrobenzenesulphonic acid (DNBSO3) or K2Cr2O7. Differences in time course were noted and these were confirmed by increase in vascular permeability and histological appearance. Failure to influence the reactions with indomethacin would appear to exclude the participation of an Arthus-type phenomenon, despite evidence of a drop in the circulating antibody levels. Increased numbers of basophils were found particularly in the DNFB/DNBSO3 reaction during its resolution. These reactions could therefore be broadly included among the cutaneous basophil hypersensitivities.