Biologic activities of bovine IgG subclasses.

With regard to our studies on the functional properties of bovine IgG1 and IgG2 antibodies, the differences were minimal when homologous systems were evaluated. Both IgG1 and IgG2 fixed bovine complement by the classical pathway, caused homologous passive cutaneous anaphylaxis, caused phagocytosis of coated erythrocytes by cultured monocytes and precipitated with an antigen having multiple unique determinants (ovalbumin). In contrast to IgG2, IgG1 caused neither adherence nor phagocytosis by freshly isolated neutrophils and monocytes. Additionally, IgG2 antibodies to DNP precipitated with DNP19ovalbumin while IgG1 antibodies formed soluble complexes with this antigen.