CpG-containing oligodeoxynucleotides induce TNF-alpha and IL-6 production but not degranulation from murine bone marrow-derived mast cells

Mast cells are sentinel cells critical to the initiation of innate immune a nd inflammatory responses, particularly at mucosal surfaces, To fulfill thi s function they can be activated by several pathogen-associated stimuli to produce cytokines with or without concurrent degranulation, We examined the ability of immunostimulatory DNA sequences including CpG motifs, which are found in increased quantities in bacterial DNA, to activate mouse bone mar row-derived mast cells (mBMMC). Mast cells were treated with a range of dos es of CpG-containing oligodeoxynucleotides or control oligodeoxynucleotides without CpG Tvithin their sequence. There was a dose-dependent increase in the production of both interleukin-6 (IL-6) and tumor necrosis factor alph a (TNF-alpha) by mast cells treated with the CpG-containing oligodeoxynucle otides. The cytokine levels induced were directly related to the number of CpG within a given length of sequence, Treatment with oligonucleotides cont aining 3CpG induced an eightfold increase in TNF production over control in cubated mast cells, Other cytokines, including granulocyte-macrophage colon y-stimulating factor, IL-4, iuterferon-gamma, and IL-12 were not induced by oligonucleotide treatment, Neither CpG containing oligodeoxynucleotides no r control oligodeoxynucleotides induced degranulation of mast cells, Bacter ial DNA from Escherichia coli also induced IL-6 from mBMMC but neither calf thymus DNA nor methylase-treated E. coli DNA had such an effect, Examinati on of the uptake of Texas red-labeled CpG and non-CpG-containing oligodeoxy nucleotides revealed that they were both similarly taken up by the mBMMC, T hese results have important implications for the mechanism by which mast ce lls respond to bacteria and for the potential role of mast cells in DNA vac cination.