Alternative complement pathway activity (ACH50) was determined
as the method described by Yanno [30]. The degree of hemolysis
and the volume of serum that gave 50% hemolysiswas used
for calculating the ACH50 using the formula: ACH50 (units/ml) ¼ 1/
K r 1/2. Where K is the amount of serum giving 50% hemolysis, r
is the reciprocal of the serum dilution, and 1/2 is the correction
factor. The assay was performed on a 1/2 scale of the original
method.