Retroviral transfection into bone marrow cells.

(A) Gene copy number analysis. DNA from bone marrow cells transfected with (+) or without (−) MFG–IL-1Ra was digested with KpnI and subjected to Southern blot analysis using theNcoI/BamHI fragment of the IL-1Ra gene as a probe. As a standard, different amounts of IL-1Ra cDNA, corresponding to 2, 1, 0.5, 0.25, and 0.1 copies per cell, were also subjected to Southern blotting. (B) Secretion of IL-1Ra from transfected cells. Bone marrow cells transfected with MFG–IL-1Ra or MFG-GC were cultured for 48 hours, and supernatants were subjected to Western blot analysis of IL-1Ra expression.