Partial purification and characterization of a colony-stimulating factor secreted by a T lymphocyte clone

The mouse T lymphocyte clone L2 secretes a minimum of 10 lymphokine activities affecting at least 5 different target cells. Large amounts of colony-stimulating factor (CSF) (8.6 X 10(6) U/ml) can be obtained by stimulating L2 cells with concanavalin A. The major CSF activity secreted by L2 cells has been enriched to a specific activity of approximately 2-4 X 10(8) colonies/mg of protein using hydrophobic-interaction, gel-permeation, ion-exchange, and lectin-affinity chromatography. This preparation of CSF contains no detectable interleukin 2, interleukin 3, or interferon. The major L2-cell CSF induces granulocyte/macrophage colonies from bone marrow cells. This GM CSF has an apparent Mr of 22,000 as determined by gel-permeation chromatography. Treatment of L2-cell CSF with proteolytic enzymes abrogates biologic activity.