Immune Haemolysis in Agar: Demonstration of the Protective Action of Antibodies.

Certain human sera contain antibodies which under some circum- stances inhibit complement dependent lysis of sensitized sheep cells. The activity of these antibodies was demonstrated by the use of agarose plates containing sensitiized sheep cells. Most human sera placed in small holes cut in the plates produced homogeneous zones of total lysis around the holes. Occasional sera produced an inner zone of unlysed cells within an outer zone of lysis. Detailed studies of three such sera showed that this appearance was due to a protective effect of natural anti-sheep cell antibodies of IgG class. [ABSTRACT FROM AUTHOR]