Cells are a subclone derived from B13.29 (first described as clone 9.9) by fusion of BALB/c spleen cells with SP2/0-AG14 myeloma cells; this hybridoma is a non-producer. B9 is a mouse B cell hybridoma line that requires Interleukin 6 (IL-6) for survival and proliferation. IL-6 is a pluripotent cytokine with multiple effects on many different cell types. It is produced by a variety of cells in response to various stimuli.