Hydrolyzed diets may stimulate food-reactive lymphocytes indogs

摘要

Hydrolyzed proteins are often prescribed for dogs with food hypersensitivity in foodelimination programs. However, the potential of these diets to stimulatelymphocyte-mediated hypersensitivity is currently unknown. In this study, two commerciallyavailable hydrolyzed diets for dogs, D-1 (Aminopeptide Formula Dry, Royal Canin Japon,Tokyo, Japan), and D-2 (Canine z/d Ultra Dry, Hill’s-Colgate (Japan) Ltd., Tokyo, Japan),were analyzed to identify residual proteins or peptides, as well as activated helperT-lymphocyte reactions in dogs with suspected food hypersensitivity. Proteins and peptideswith molecular weights >1 kDa (majority 1.5–3.5 kDa) were detected in both dietextracts with sodium dodecyl sulfate polyacrylamide gel electrophoresis, and sizeexclusion chromatography. When peripheral blood mononuclear cells (PBMC’s) from 316 dogswith suspected food allergies were cultured with hydrolyzed diet extracts, flow cytometryanalysis revealed detectable levels of CD25 helper T-lymphocytes stimulatedby D-1 and D-2 in 91 of 316, (28.8%), and 75 of 316 (23.7%) samples, respectively. Thesedata indicated that the extracts contained proteins or peptides large enough to activatethe lymphocytes. The percentages of CD25 helper T-lymphocytes stimulated byD-1 and D-2 extracts increased to 38.7% and 29.6%, respectively, in 186 of the original316 samples (186/316, 58.9%), also reactive to poultry-related antigens. Thus, bothpoultry-related antigens, and D-1 and D-2 diet extracts may activate helper T-lymphocytes.These results demonstrate that hydrolyzed diets may contain proteins that stimulate helperT-lymphocytes, and may not be effective for treating all dogs with foodhypersensitivity.