The Antibody Response in the Human Being after Injection with Normal Horse Serum

After the injection of normal horse serum in the human being, serum sickness occurs even more regularly than in cases treated with the various immune sera, but this is not accompanied by the production, to any notable degree, of circulating antibodies of the various types that are regularly to be demonstrated after the administration of immune serum and its resulting serum sickness. Since normal horse serum therefore appears to be weakly antigenic, and immune serum highly antigenic for the human being, one must assume that this difference is the result of some alteration in its antigenic characteristics produced during the course of the immunization or of its preparation for use; or that the specific antibody which is responsible for the phenomenon of serum sickness has not yet been identified; or that this phenomenon is not in any way dependent on the presence of the various known antibodies to normal horse serum.