Heterogeneity of Sheep Diphtheria and Tetanus Antibodies

Abstract

Summary The ultracentrifugal patterns of ovine immune globulin revealed two peaks, the major peak having a sedimentation coefficient (s20, w) of 6.6 S while the smaller peak sedimented at 18 S. Heat treatment (65°C for 1 hr) destroyed the globulin sedimenting at 18 S. The sedimentation pattern of the 6.6 S globulin was unaffected. Globulin sedimenting at 6.6 S had a molecular weight of 174,000. The faster sedimenting 18 S globulin had a molecular weight of about 1 million. The administration of diphtheria and tetanus toxoids to sheep was followed by the production of heat labile 18 S antibodies, which reached a peak titer on the 7th day. Heat stable 6.6 S antibodies were not detectable until the 9th day and their titer rose sharply thereafter. Early response ovine antitoxin appeared to be composed largely of 18 S antibodies. Most of the antibody activity of hyperimmune sheep antitoxin was found to be concentrated in the 6.6 S globulin. The antibody activity of electrophoretically separated globulin fractions of higher mobility was destroyed by heating at 65°C for 1 hr. The titers of globulin fractions of lower mobility were enhanced by the application of this level of heat. Chromatographic subfractionation of purified 6.6 S γ2-globulin revealed the presence of tetanus antibodies in two subfractions, one of low and the other of intermediate electrophoretic mobility. Diphtheria antibodies were concentrated in a single fraction of intermediate mobility.