Augmentation by Bursaphelenchus xylophilus, a Pine Wood Nematode, of Polyclonal IgE Production Induced by Lipopolysaccharide Plus Interleukin-4 in Murine Splenocytes

<i>Bursaphelenchus xylophilus</i> (<i>B. xylophilus</i>) is a pine wood nematode that is known to cause pine wilt disease. We report here that <i>B. xylophilus</i> extracts augmented the polyclonal immunoglobulin E (IgE) production induced by lipopolysaccharide (LPS) plus interleukin-4 (IL-4) both in murine splenocytes and purified B cells as determined by ELISA and ELIspot assays, but they did not cause such a promotion in the absence of either LPS or IL-4. We also observed that the antigen-nonspecific IgE levels were increased in sera of mice treated with <i>B. xylophilus</i> extracts, which were comparable to those of <i>Ascaris suum</i> extracts. These findings suggest that administration of <i>B. xylophilus</i> extracts could suppress allergic diseases via a saturation of mast cell Fcε receptors or/and an inhibition of antigen-specific IgE synthesis to the allergen by a polyclonal response.<br>