Canine C-reactive protein (CRP) does not share common antigenicity with human CRP

Differences in antigenicity between human and canine C-reactive proteins were investigated by Western blotting analysis. It was confirmed that several commercial anti-human CRP sera reacted with canine CRP. However, 34 anti-canine CRP sera prepared by immunization of rabbits and goats with canine CRP all reacted with canine CRP but not with human CRP in either immunoelectrophoresis or Western blotting. Immunization with human CRP produced a cross-reacting antibody that reacted with canine CRP. Conversely, immunization with canine CRP did not produce a cross-reacting antibody that reacted with human CRP. These findings may be interpreted as showing that, while canine and human CRPs do not share common antigenicity, they do contain structurally similar antigenic determinants.