The production of precipitating antiglobulin reagents specific for the subclasses of human IgG.

Precipitating antisera against the four subclasses of human IgG were prepared by immunizing different species of animals (monkeys, rabbits, chickens, guinea-pigs and sheep) with whole IgG or Fc fragments. Freund's complete and incomplete adjuvant and Al(OH) were used to enhance antibody formation. In most of the experiments with rabbits, immunization against a particular subclass was accompanied by induction of unresponsiveness to the other subclasses. Different animal species showed distinct preferences for production of certain IgG subclass antisera. Anti-IgG could quite easily be produced in each of the animal species tested (monkey, rabbit and guinea-pig). Anti-IgG and anti-IgG could be raised in monkeys and, with greater efforts, in rabbits. Anti-IgG could easily be raised in guinea-pigs and with difficulty in rabbits. In our hands monkeys did not react to IgG, possibly because only Gm(f+) paraproteins were used; experiments with rabbits and guinea-pigs showed that antibody formation against IgG was promoted by the presence of the Gm(a) marker. The Gm(n) marker was found to influence anti-IgG formation to an even greater extent: no subclass-specific antibodies were obtained when Gm(n-) IgG paraproteins were used as antigen. Apart from IgG subclass-specific antibodies the following additional antibodies were often found: antibodies directed to a combination of a certain heavy chain and a kappa light chain in monkeys; antibodies specific for one or more antigenic determinants common to IgG and IgG in monkeys and rabbits immunized with IgG; antibodies specific for one or more antigenic determinants common to IgG and IgG in guinea-pigs and rabbits immunized with Gm(f+) IgG.