Serum sickness. III. Characterization of antigens

1. 1. Patients developing primary serum sickness following prophylactic administration of tetanus antitoxin may precipitate two antigenic components of horse serum. In agar electrophoresis one of these components has the migration rate of an alpha globulin; the other migrates as a gamma globulin. The alpha globulin antigenic fraction appears to be more important in the tanned cell hemagglutination reaction. 2. 2. Commercially available "purified" antitoxins retain both of these antigens of whole horse serum. 3. 3. Precipitation and gel precipitation studies indicate that most patients with primary serum disease react, primarily, if not entirely, to antigens other than the therapeutically active antitoxin.