Interaction of bovine immunoglobulins with complement.

Whereas complement (C) in rabbit serum (CR) was bound by bovine antibodies in seven different IgG1 preparations, only two IgG1 preparations could bind the C in guinea pig serum (CGP). Addition of the Clq component of CR to CGP was alone sufficient to render the C-cascade in CGP activable in the presence of bovine erythrocytes sensitized with specific antisera, i.e. reagents. Normal bovine serum was also capable of restoring the haemolytic activity of CGP. However, the bovine serum was much more temperature sensitive than was CR and, as was observed in the sera from MZ twins, it showed considerable variation both in titre values and in prozones when added to CGP.