Complement-Fixation Technique: II. THE TITRATION OF WASSERMANN ANTIGEN.

After material has been produced for use as an antigen in a complement fixation test it is necessary to find out if the finished product has any complement-fixing ability in the presence of a serum containing a suitable antibody. Moreover, the proposed antigen must not have any undue anticomplementary property, and the " gap" between its anticomplementary titre and its complement fixing titre must be wide enough to permit its use with safety in the test. Finally, the product should be titrated by the method of optimal proportions. It is therefore suggested that in the standardization of any proposed antigen the following three steps should be taken.