Participation of an early component of complement and Hageman factor in C3 destruction by zymosan

The contributions of the early components of complement and the clotting system to zymosan-serum interaction were examined with sera deficient in certain proteins of these systems. Incubation with zymosan of minimally diluted C2-deficient serum, Hageman factor-deficient serum, or serum of a sex-linked agammaglobulinemic patient resulted in minimal C3 destruction. Reconstitution of the serum with either C2 or Hageman factor fragments, respectively, yielded destruction of C3 comparable to that obtained with normal serum. Analysis of the zymosan particles after incubation with the sera indicated that C 1 was present as assessed by transfer and the generation of the classical convertase with C4 and C2. In addition, an activity capable of partially correcting the coagulation defect of Hageman factor-deficient plasma but not plasma thromboplastin antecedent-deficient plasma was present. C 1 was absent from complexes formed in agammaglobulinemic serum and Hageman factor from complexes formed in Hageman factor-deficient serum. A pH 7.0, 0.6 M NaCl eluate of the complexes revealed that normal eluates possessed antigenically detectable properdin, factor B, C3, and IgG, while eluates from complexes formed in deficient sera possessed only IgG.