An in vitro line of the B cell tumor BCL1 can be activated by LPS to secrete IgM1.

An in vitro line of the B cell tumor BCL1 was developed. The cell line carried u-, S-, and A-chains on the cell surface as judged by analysis of surface iodinated proteins but did not secret Ig. ASfter stimulation with LPS, limpid A, or bacterial lipoprotein, 20 to 40% of the tumor cells matured to IgM secretors when detected in a plaque assay. Two other polyclonal B cell activators, namely dextransulphate and PPD, had at most a marginal stimulatory effect. The ability of the cells to become activated to IgM secretion as well as the expression of cell surface IgM and IgD makes the BCL1 unique among murine B cell tumors.