DEVELOPMENT OF AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE DETECTION OF IGG SUBCLASSES IN THE SERUM OF NORMAL AND DISEASED DOGS

The present study describes the development of an enzyme-linked immunosorbent assay capable of quantifying serum antibody of all four canine IgG subclasses. A panel of subclass-restricted and subclass-specific monoclonal antibodies was used to measure IgG subclasses in the serum of healthy dogs, as well as in dogs with a range of clinical diseases. The subclasses have been redefined as IgG(1), IgG(2), IgG(3) and IgG(4) based on a comparison with the relative concentration and electrophoretic mobilities of human IgG subclasses. In serum samples from healthy dogs, the concentration of IgG(1) (mean, 8.17 +/- 0.95 mg ml(-1)) and IgG(2) (mean, 8.15 +/- 3.16 mg ml(-1)) were very similar and considerably higher than the levels of IgG(3) (mean, 0.36 +/- 0.43 mg ml(-1)) and IgG(4) (mean, 0.95 +/- 0.45 mg ml(-1)). There was no apparent difference in the level of subclasses between the different breeds comprising this normal population. Sera from dogs with a range of immune-mediated or inflammatory diseases all had markedly elevated levels of IgG(2) (more than 13 mg ml(-1)), but IgG(1) decreased (less than 4 mg ml(-1)) to levels below the normal range.