Purification to apparent homogeneity of murine interleukin 1

Interleukin 1 was purified to apparent homogeneity from the culture fluid of P388D1 cell line macrophages by a procedure involving ammonium sulfate fractionation, phenyl Sepharose and Ultrogel AcA54 chromatographies, and preparative isoelectrofocusing. The interleukin 1 was purified more than 300-fold to a specific activity of approximately 1 X 10(6) U/mg protein. The purified interleukin 1 exhibited microheterogeneity. Three charge species, which we have termed alpha, beta, gamma, were resolved by Tris-glycinate discontinuous polyacrylamide gel electrophoresis. The partial amino acid content of the alpha species of interleukin 1 was determined. On the basis of the purification data, it appears that interleukin 1 is biologically active within the 10(-11) to 10(-10) M concentration range. The success of the purification was due in part to the use of a superinduction protocol that resulted in the production of interleukin 1 at a rate of approximately 1 microgram/24 hr/4 X 10(6) P388D1 cells.