Granulocyte-macrophage colony-stimulating factor produced by an inducible murine T-cell hybridoma: molecular properties and cellular specificity.
The properties of granulocyte-macrophage (GM) colony stimulating factor (CSF) produced by a mouse T-cell hybridoma (T19.1) as a result of stimulation by concanavalin A have been investigated. Stimulation of T19.1 cells (2 x 10(6)/ml) with concanavalin A (5 microgram/ml) in the absence of serum for 24 h led to the production of colony stimulating activity (100 ng/ml). The molecular and biological properties of the hybridoma GM-CSF were compared with similar molecules produced in vitro by mouse lung or muscle cells. When bone marrow cells were stimulated by T19.1 conditioned medium (CM) only colonies containing granulocytes (G), macrophages (M), or a mixture of both cell types developed. The distribution of colony types (G, G/M or M) was dependent on the concentration of T19.1 CM in the same way as the GM-CSF from mouse lung conditioned medium. Similarly GM-CSF from T19.1 CM was also able to stimulate the initial proliferation of other hemopoietic progenitor cells and induce differentiation in the myelo-monocytic leukemic cell line (WEHI3B). The apparent molecular weight of GM-CSF in T19.1 CM as determined by gel filtration on Ultrogel AcA44 was 24,000. Using high performance liquid chromatography, GM-CSF from T19.1 CM eluted at the same apparent molecular weight (32,000) on molecular sieve columns and acetonitrile concentration on reverse phase columns as the GM-CSF from mouse lung and muscle CM. The level of production of GM-CSF and the similarity to the molecule from mouse lung CM indicated that this continuous cell line should be useful for preparing GM-CSF in suitable quantities for structural analysis and in vivo testing.