Biochemical and cellular changes in skin and lymph during Arthus and mixed hypersensitivity reactions in rabbits.

The object of this investigation was to determine whether the pathological events which occur during the Arthus and mixed hypersensitivity reaction could be monitored biochemically and whether changes in enzyme concentrations would reflect the severity of tissue damage either in the skin itself or in the lymph draining the lesion. The initial increase in vascular permeability which resulted in oedema formation in the tissue was reflected by a large increase in the water and protein content of the tissues, however, there was no increase in either the protein concentration or flow of the lymph. The increases in the total enzyme content in the lesion could not always be related to the macroscopic appearance of the reaction site. However, the severity of the reaction did appear to be related to the concentration of cathepsin D in the oedema fluid present at the reaction site. Although the release of enzymes was reflected in the local lymph in the case of LDH and beta-glucuronidase there was no increase in of the concentration cathepsin D in the lymph draining the lesion.