Consumptive opsoninopathy: possible pathogenesis in lethal and opportunistic infections.

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.