Changes in bovine immunoglobulin levels during a response to homologous erythrocyte membrane antigen

Changes in serum immunoglobulin levels of IgG1, IgG2 and IgM were studied in cows immunised with a butanol extract of bovine erythrocytes. Donor and recipients were matched to differ at only one known red cell antigen, the V antigen, and after the first course of injections a weak antibody response to V antigen was associated with elevated levels of IgG2 immunoglobulins. A second course of injections of V antigens together with Bordetella pertussis led to a stronger and more longlasting antibody response to V and this was associated with elevated levels of IgG1 and correspondingly decreased levels of IgG2. One cow calved during the period of investigation and it was found that even though serum antibody levels disappeared three weeks before calving there was a high antibody titre in the colostrum which was passed on to the calf. The loss of serum antibodies before calving was associated with a fourfold drop in serum IgG1 and an increase in serum IgG2 levels.