Nonimmune chemotaxis in vivo: inhibition by complement depletion with cobra factor.

Wistar rats were depleted of complement components using purified cobra venom factor (CoF) administered over a 30-hour period by intraperitoneal injection. Complement depletion was confirmed by immunodiffusion assay, hemolytic assay and inhibition of the reverse Arthus reaction. Rats depleted to below 3% of their normal serum complement level showed marked inhibition of chemotaxis into inflammatory fluid produced in polyvinyl sponges 24 hours after implantation into the dorsal subcutaneous region. Subsequent studies were done to test the effect of high local concentrations of CoF on the microcirculation, the neutrophil and the connective tissue. Local exposure of these tissues and cells to CoF in vivo had no inhibiting effect on chemotaxis. Cobra venom factor did not affect neutrophil survival in vitro or in vivo. The most likely hypothesis is that CoF works by depleting complement and that in vivo chemotaxis of the nonbacterial, nonimmune type is complement dependent to the extent of 60 to 80%. The system described allows for quantitative determination of chemotaxis in vivo.