FIG. 4.

(A) Effect of increasing concentration of Ca²⁺ on the C1q binding in pNHS. (B) Effect of increasing concentration of Mg²⁺ on the C3 deposition in pNHS. In both experiments, pNHS was diluted 1:1 in the presence of a final SPS concentration of 0.5 mg/liter. The samples were assayed at 10% pNHS and carried out as described in Materials and Methods. Controls were pNHS without SPS application. The C3 deposition was determined as OD_490-650 units. Error bars indicate two times the standard deviation of double determinations.