Cross-reactivity of human monoclonal antibodies with canine peripheral blood mononuclear cells

In drug development, the dog is often used as a model for non-rodent preclinical safety studies. In particular, immunophenotyping in dogs can be important to characterize the toxicological profile of a test item. A wide range of antibodies specific to surface antigens is needed, however, commercially available antibodies to dog are scarce. To date, numerous studies have reported the cross-reactivity of human monoclonal antibodies with canine peripheral blood mononuclear cells (PBMC). In this study, we aimed to increase the number of canine-specific antibodies and took a rather novel approach to further determine cross-reactivity of 378 human recombinant antibodies lacking Fc regions to surface antigens on canine PBMC. The screening resulted in 30 human monoclonal antibodies well reactive to canine PBMC. Sequence homology of the targeted human and canine antigens was analyzed with Basic Local Alignment Search Tool. Thirteen human cross-reactive antibodies of interest were analyzed with cells from canine whole blood in combination with lineage markers. Finally, ten antibodies were identified as useful markers for the application in dog. Except for CD27, the remaining nine antibodies are already commercially available human cross-reactive antibodies. This study provides a new source for all ten antibodies described here.