1. The injection of horse serum either in small or in large amounts in human beings is always followed sooner or later by the development of hypersensitiveness of the skin to subsequent injections of horse serum. For the development of this reaction serum disease is not essential.
2. The blood serum of most patients who suffer from an attack of serum disease following injections of horse serum shows anaphylactin and precipitin for horse serum.
3. Anaphylactin and precipitin cannot be demonstrated in the blood serum of patients treated with horse serum who do not later present symptoms of serum sickness.
4. The appearance of anaphylactin and precipitin precedes shortly recovery from the disease.
5. With the appearance in the serum of antibodies to horse serum in great concentration, the antigen rapidly diminishes or disappears.
6. It is probable that the extrusion of these antibodies into the circulation is the result and not the cause of serum sickness. Their presence serves to neutralize or destroy the antigen and thus determines the recovery from serum sickness.