Purification of serum proteins from lymph node cell extracts with permeability activity characteristic of the lymph node permeability factor.

The biologically active aqueous extract of rat lymph node cells, previously shown to contain the lymph node permeability factor LNPF, was fractionated by gel filtration and ion exchange chromatography. The fractions obtained were characterized by immunoelectrophoretic analysis and found to contain a wide range of serum proteins. The ability of the fractions to increase vascular permeability to plasma protein was measured. Activity was found to be distributed among several serum proteins and was mainly associated with albumin, though minor quantities of γ-globulin were also found to have high specific activity. Comparative analysis of γ-globulin and albumin prepared from lymph node cell extract and serum, respectively, suggested that the active factor was most likely to be released from the lymph node cells to form complexes with these proteins.