Properties of Guinea Pig 7s Antibodies I. Electrophoretic Separation of Two Types O]~ Guinea Pig

Antibodies can be considered to be molecules with two distinct sets of properties: the capacity to react specifically with antigen, and the capacity to mediate a variety of biological reactions. Some of these are: anaphylaxis, which in the guinea pig may depend upon the ability of these molecules to react with unidentified tissue receptors (1) or cell lysis (2, 3) and opsonization (4, 5) which results from their ability to fix complement components. The combination of these two sets of properties on the same molecule ensures that the biological activity mediated by antibodies is selectively directed.