The indentification of natural and induced bacterial antibody with the serum components in sheep.

The association of antibody with y-globulins was first demonstrated electrophoretically in the serum of rabbits immunized with egg albumin; Tiselius & Kabat (1939) and Enders (1944) found antibodies against a wide range of virus, toxin and bacterial antigens in the y-globulin prepared from pooled human plasma by ethanol precipitation. Kekwick & Mackay (1954) used one of these antibodies, the Salmonella H agglutinin, as a means of testing the amount of y-globulin in human globulin mixtures during the development of a method of fractionation of human plasma in aqueous systems containing ether in which the y-globulins were concentrated in fraction G 3. When the method was applied to the sera of other animals, it was found that although, as might be expected from the work of Gibson (1930), an agglutinin against one or more Salmonella was present in the pooled sera from most mammalian species, this agglutinin was not necessarily associated with the fraction G 3, as in human serum. In normal sheep serum the agglutinin was in the fraction G 2, which was predominantly aand figlobulins, and the fraction G 3, predominantly yglobulin, had no detectable agglutinin (Mackay, 1955). It was of some interest therefore to know whether the antibody produced by the injection of a bacterial antigen into sheep would be found in the same fraction as the natural agglutinin, and if this was not so, whether the natural agglutinin could be separated from the induced antibody by this method. The term natural agglutinin in this work is used for the agglutinin found ab initio in the sheep sera, and induced antibody the agglutinin produced by the injection of a bacterial vaccine. The author appreciates the fact that both agglutinins may have been formed as an immune response to antigens introduced by different routes. In the course of the work serum and serum fractions from normal sheep, as well as from sheep which had been immunized, were examined electrophoretically. The natural agglutinin in serum and serum fractions of the immunized sheep was also assayed, to find out whether the injection of bacteria with an antigen different from that specific for the natural agglutinin had any effect on the serum titre of the natural agglutinin.