Evaluation of Canine Erythrocyte Surface Antigens and Morphological Alterations Induced by Trypsin Treatment

Dogs have multiple blood type antigens, among which DEA 1, DEA 4, and Dal can induce severe acute hemolytic transfusion reactions. Various antigen modulation techniques have been developed to reduce immunogenicity and transfusion reactions. Recently, trypsin has been suggested as a potential tool for modulating the antigenicity of DEA 1 in veterinary medicine. Following this rationale, this study aims to evaluate the effects of trypsin on the antigenicity of these three antigens. A 50% RBC suspension treated with 1 mg/mL trypsin was incubated at 37 °C for 120 min. The antigenicity of DEA 1, DEA 4, and Dal was assessed using blood typing assays before and after trypsin treatment. As a result, trypsin did not reduce the antigenicity of DEA 1 and DEA 4; instead, trypsin significantly increased their antigenicity (<i>p</i> = 0.008) and promoted agglutination, whereas Dal exhibited a significant reduction in antigenicity (<i>p</i> = 0.008). Quantitative morphological parameters obtained from an automated hematology analyzer revealed no significant differences between trypsin-treated and negative control groups. However, morphological scoring under an optical microscope showed significantly fewer echinocytes in the trypsin-treated group (<i>p</i> = 0.008). Consequently, broad-spectrum proteases like trypsin are unsuitable for universal blood production due to their variable effects on erythrocyte surface antigens.