DEMONSTRATION OF TRYPTASE IN BOVINE CUTANEOUS AND TUMOR MAST-CELLS

We examined three tissue samples from each of four cows with non-lesio nal skin, tissue samples from a cow with multiple cutaneous mast cell tumors, and samples from another cow in which mast cells were infiltra ting multiple lymphosarcomas of the skin, for the presence of tryptase and chymase by enzyme cytochemical and immunohistological methods, Th e enzyme activities of tryptase and chymase were tested using bobenzox y-glycilglycil-L-arginine-2-naphthyl-amide (Z-Gly-Gly-Arg-NA) and naph thol-AS-D-chloroacetate (N-AS-D-CA) as substrates, respectively, Trypt ase reactivity could be demonstrated in frozen and Carnoy-fixed paraff in sections, Chymase reactivity was seen in neither frozen nor paraffi n sections of formalin- or Carnoy-fixed skin tissues, Antibody linkage with a polyclonal rabbit anti-human skin trypase antibody was highly specific in bovine normal cutaneous, infiltrating, and tumor mast cell s, More than 90% of the tumor mast cells were distinctly trypase-posit ive, With alcian blue, only slightly more than 10% of the mast cells s tained dearly positive and with methylene blue hardly any staining of mast cell granules could be demonstrated, No antibody labeling of mast cell granules in any of the tissue sections was detected by the use o f rabbit anti-dog chymase antiserum, These results indicate that there is a striking antigenic similarity of bovine trypase to its canine an d human equivalents, The demonstration of trypase is an important tool in confirming the diagnosis of undifferentiated mast cell tumors, In contrast to other species, chymase appears to be completely absent in bovine skin mast cells.