| Abstract: | Several IL 3-dependent murine bone marrow-derived cell lines can be stimulated to grow with antigen-antibody (Ag.Ab) complexes. The Ag.Ab complexes induced lymphokine gene expression and the synthesis of IL 2, GM-CSF, IL 3, and BSF-1 (IL 4). The lymphokines produced by these IL 3-dependent cells appeared to stimulate their own growth, as both IL 3 and BSF-1 (IL 4) stimulated the growth of IL 3-dependent cells. Ag.Ab complexes also stimulate the growth of primary cultures of bone marrow cells that have been previously activated with IL 3. Normal bone marrow, IL 2-, and GM-CSF-dependent bone marrow cell lines could bind Ag.Ab complexes, but binding did not result in the induction of lymphokine synthesis or cell growth. Hyperimmune serum from mice also stimulated lymphokine synthesis and cell growth in IL 3-dependent cells, and the stimulatory activity was removed by treatment with Staphylococcus aureus protein A, suggesting the presence of Ag.Ab complexes. |
