CpG-oligodeoxynucleotide-resistant variant of WEHI 231 cells

Bacterial DNA and synthetic single-stranded oligonucleotides having unmethy lated CpG motifs (CpG-ODN) powerfully stimulate cellular immune responses b y an unknown mechanism. There is evidence that internalization of the nucle otide is required for activity. Both CpG-ODN and engagement of CD40 protect s WEHI-231 murine B lymphoma cells from apoptosis induced by antibody to su rface IgM, and both agents induce interleukin-6 (IL-6) production by these cells. We now report the isolation of CpG-ODN-resistant subclones (designat ed CR) front WEHI 231 cells, as well as subclones that are sensitive to CpG -ODN (designated CS), CR clones completely fail to respond to CPG-ODN but t hey retain the capacity to respond normally to engagement of CD40. CR cells incorporate CpG-ODN into small, acidified perinuclear vesicles in the same way as do the parent WEHI 231 cells. The CR, CS, and WEHI 231 cells all ha d identical cytogenetics, The described CR clones have a stable and specifi c defect in the mechanism responsible for the intracellular recognition and response to CpG-ODN, suggesting that they harbor a mutation that disables the CpG-ODN detection mechanism. These clones may be useful to determine at a molecular level which proteins and cell components are required for immu ne cells to detect and respond to CpG-ODN.