An investigation was undertaken in this laboratory with a view to precipitating the antibodies from antityphoid sera by means of a specific antigen and subsequently dissociating this antigen-antibody complex, obtaining the antibodies in a solution as free from foreign protein as possible.
As is well known, a number of antityphoid sera have been prepared and occasionally physicians have reported good results with them, but their use has never been general. In order to be successful with a bactericidal serum it seems necessary to inject large amounts. For example, Cole (1), in the treatment of pneumonia, by using very large quantities of antipneumococcus serum (from 190 to 700 cc.) has had success where others have failed. Owing to the danger of “serum sickness” following the injection of large amounts of horse serum, physicians have hesitated to treat their patients with it.