The purification and characterization of a lymphokine chemotactic for lymphocytes--lymphotactin.

Aqueous extracts of the thymus from vaccinated calves contain a protein specifically chemotactic for lymphocytes (lymphotactin). Lymphotactin has been isolated and purified by ethanol fractionation, ultrafiltration, isoelectric focusing, and preparative acrylamide gel electrophoresis. Its isoelectric point is 5.9, and the molecular weight by both SDS electrophoresis and exclusion chromatography is about 10,500. The purified sialoprotein is homogeneous at three different pH's in acrylamide gel electrophoresis. As little as 1 microgram of this material intraperitoneally wlll produce massive lymphocyte infiltration within 4 h in vivo.