Further Studies on a Permeability Factor Released from Guinea-Pig Serum by Antigen-Antibody Precipitates: Relationship to Serum Complement

Abstract

Treatment of fresh guinea pig serum with an antigen-antibody precipitate (Ag/Ab) leads to the formation of a permeability factor which has been referred to as PF/P (Davies and Lowe, 1960). PF/P is formed within 5 minutes of the addition of serum in amounts dependent on the concentrations of serum and Ag/Ab. PF/P activity may be eluted by saline from Ag/Ab which has been treated with serum. Fractionation of guinea pig serum by a variety of methods reveals that gamma-globulin is a potent mediator of increased capillary permeability (Davies and Lowe, 1961). Ag/Ab will not further activate gamma-globulin nor will it activate serum from which gamma-globulin has been removed or such serum to which the gamma-globulin has been re-added. It appears that some substance necessary for the formation of PF/P is destroyed when serum is fractionated to remove gamma-globulin. No PF/P can be formed from heated serum or from serum dialysed against phosphate buffer ([mu] =0.02; pH 5.4). The suitability of serum as a source of PF/P is also impaired by ageing, removal of Mg++ or by treatment with formaldehyde or di-isopropylphosphofluoridate. It is concluded that all components of serum complement are necessary for the formation of PF/P.