Ons (mannanbinding activity) and MBL C4 cleavage activity in sera from 35 healthy adult volunteers of Caucasian, Asian, Hispanic or AfricanAmerican ancestry (females, n = 20). The sample had a 3.7 log10 range of MBL concentrations (0?,424 ng/mL) that were strongly correlated with the concordant MBL C4 cleavage values (0?7,468 U/mL; r2 = 0.91). The sample included three individuals with homozygous