(Eponymously named for the German physician and bacteriologist, August P. von Wassermann, 1866-1925. Often abbreviated WR.)
Wassermann's reaction is a formerly very commonly used serological test for the presence of antibodies to syphilis in a blood sample. It was introduced by Wassermann in 1906, and soon came into widespread use, particularly in examining pregnant women.
As antigen, Wassermann made use of an extract of liver cells from dead syphilitic children; it was later shown that extracts of a number of different healthy animal tissues (e.g., muscle tissue from the hearts of calves) could be used as antigens, due to their content of particular phospholipids (called cardiolipids).
As a test, Wassermann's reaction is not sufficiently specific. For instance, it shows unreliable positive reactions in the presence of autoimmune diseases. Since the 1960s, therefore, Wassermann's reaction has been supplemented with a number of other tests for detection of antibodies to the syphilis spirochete, Treponema pallidum.