Electrophoretic and serological analysis of mouse and rabbit antisera to zymosan or inulin treated with foetal lamb serum.

Most mouse antisera raised to zymosan treated with FLS containing Ca2+ and Mg2+ precipitated C3 and two other proteins from electrophoresed sheep serum. Rabbit antisera to zymosan-FLS precipitated C3 and three sheep serum proteins. All these antisera agglutinated sheep E-rabbit A complexes sensitized with sheep C at room temperature. Mouse antisera to zymosan treated with FLS containing Mg2+-EGTA and mouse antisera to inulin treated with FLS containing Ca2+ and Mg2+ or Mg2+-EGTA, precipitated only C3 from electrophoresed sheep serum, but did not agglutinate sheep E-rabbit A-sheep C. These results, together with antiglobulin studies indicate that zymosan, probably through a reaction with natural antibody in the FLS can activate sheep C by a mechanism that involves a Ca2+ and Mg2+-dependent pathway. In the presence of Mg2+-EGTA, zymosan and inulin activate sheep C via a Mg2+-dependent pathway. The results also show that antisera that will precipitate sheep C3 from electrophoresed sheep serum can be raised by immunizing mice and rabbits with inulin that has been treated with FLS or zymosan treated with FLS containing Mg2+-EGTA.