In 1933, Tillett and Garner1 found that certain strains of betahemolytic streptococci produce a substance capable of liquefying human fibrin and demonstrated the presence in human serum of a specific antibody that was termed antifibrinolysin. Antifibrinolysin is measured by the time required for an effective strain of the organisms to produce complete lysis of the subject's plasma clot. The clot of a normal person is completely lysed in from twenty to sixty minutes, while that of a patient convalescing from an infection with beta hemolytic streptococci may resist lysis for twenty-four hours or more. The blood serum of such a patient is considered to have a high content of antifibrinolysin. Intermediate lysing times represent corresponding levels of antibody.
Applying this test to a series of mothers and newborn infants, Lippard and Wheeler (1936)2 found that the plasma clots of half of the newborn infants showed a definite prolongation