Human granulocyte-macrophage colony-stimulating factor (GM-CSF) transgene expression in T lineage cells. (A) Map of the 10.5 kb Xho I-Hind III fragment of the human GM-CSF locus used to make transgenic mice. (B and C) ELISAs of human GM-CSF expression in cultures of transgenic splenocytes (B) and previously activated T blast cells (C). The relative level of human GM-CSF expression per gene copy is expressed as (human GM-CSF/mouse GM-CSF)/(number of copies of human GM-CSF transgene/two copies of mouse GM-CSF transgene). In each case cells were stimulated for 15 h with 20 ng/ml PMA and 1 μM A23187. Error bars indicate standard error. The number of copies of the transgene is displayed below each line in panel C.