Fig. 1.

Fixation of murine complement by HBsAg/Ab IC. Graph demonstrating binding of the opsonized HBsAg/Ab IC to the solid phase ligand (polyclonal antimouse C3) via C3b. There is negligible binding of the HBsAg/Ab IC when treated with heat inactivated normal mouse serum (HINMS) or PBS rather than normal mouse serum (NMS). HbSAg alone treated with NMS does not bind significantly. This demonstrates that only the HBsAg/Ab IC was able to fix complement in the form of C3b.