Properties of the serum factor involved in the precipitation reaction with Staphylococcus capitis.

The serum factor was precipitated by both Rivanol and ammonium sulphate, and it bound to both DEAE-cellulose and Blue-Sepharose CL-6B from which it subsequently could be eluted. Immunoelectrophoresis showed that the serum factor had alpha 1-mobility, and isoelectric focusing indicated an apparent isoelectric point of 5.2. Purification by ultracentrifugation, followed by agarose chromatography, showed that the serum factor is present in the high density lipoprotein fraction of serum.