Mary Ann McClellan

Serum levels of properdin, Factor B and C3 and the ability of these sera to opsonize E. coli 075 were measured in 17 patients with surgical infections ranging in severity from mild to fatal. There was good direct correlation between severity of infection, serum levels of properdin and C3, and the ability of the serum to support opsonization. The levels of Factor B were not significantly reduced when measured by radial immunodiffusion, but immunoelectrophoresis showed conversion. Restoration of full opsonic activity was accomplished only by the addition of a combination of C3, Factor B, and properdin in excess. The findings provide evidence that severe bacterial infection causes a consumption of opsonic proteins which may result in a reduced ability of the patient's serum to opsonize bacteria and thereby further increase susceptibility to infection.

Experiments were performed to measure the stability of opsonins during storage of whole blood collected in CPD solution and stored at 4 C. Three units were collected, and aliquots removed and recalcified on days 0, 3, 7, 14, 21, and 28. Reconstituted serum was immediately frozen and stored at -70 C. The ability to opsonize Escherichia coli 075 and Pseudomonas aeruginosa immunotype 1, both of which require activation and utilization of the alternative pathway of complement for opsonization, were performed simultaneously for each organism and for each unit. Results showed that there was a slight but insignificant reduction in opsonic strength during storage for up to 28 days. The results indicate that standard collection and storage conditions using CPD as the anticoagulant retains functional activity of the alternative pathway. C3 measured by radial immunodiffusion using antisera against the B antigenic determinant showed that C3 had not been converted during storage.