Fig. 2.
Enhancement of C3 deposition onto Neisseria meningitidis W135 upon properdin addition to various sera during opsonization. The meningococci were incubated with sera of either eight properdin-deficient persons without previous meningococcal disease (– NmD), or 10 properdin-deficient persons with previous NmD (+ NmD), or 20 controls or six late complement component deficiency (LCCD) persons (all without previous NmD) in the presence or absence of 2·5 μg/ml purified properdin. The increase in C3 deposition onto meningococci is presented as ratio of the OD450nm of sera reconstituted with purified properdin relative to that of unreconstituted sera. The differences between the group of properdin-deficient persons without previous NmD and the properdin-deficient persons with previous NmD and controls were significant (P = 0·01, and P = 0·0003, respectively) as well as the differences between the LCCD group and controls (P = 0·004). Blocking the classical complement pathway by addition of MgEGTA during the incubation abolished the enhancing effect of properdin supplementation. Symbols represent the mean of duplicate measurements from serum of individual persons within one experiment; means of groups are indicated by horizontal bars.