Guinea pig antibody to C3 component of the sheep complement produced by immunization with a heat-inactivated sheep serum--alcian blue complex.

Normal sheep serum or serum heated at 56 degrees C for 30 min were added to alcian blue solutions. The optical density of alcian blue-heated sheep serum complexes formed were 2-4 times greater than those obtained with unheated serum. Most guinea pigs immunized with alcian blue-heated sheep serum complexes produced antibodies that precipitated the third component (C3) of sheep complement (C') from electrophoresed sheep serum. These antisera also hemagglutinated sheep erythrocyte--rabbit antibody complexes treated with sheep serum (C'). Guinea pigs immunized with alcian blue-normal sheep serum complexes did not react with electrophoresed sheep serum nor with sheep C' in the hemagglutination test.