B cell mitogenic activity of house dust mite, Dermatophagoides farinae, antigens

The effect of mite antigens on murine and human lymphocytes was studied in vitro. Antigens prepared from Dermatophagoides farinae feces and bodies stimulated normal murine spleen cells to proliferate in a dose-dependent manner. The responder cells are B cells, because the response was reduced by the treatment of spleen cells with anti-immunoglobulin antibody and complement, but not with anti-Thy 1 antibody and complement. Furthermore, nylon column-purified T cells did not respond. The stimulation of B cells with mite antigens was not due to the contamination of lipopolysaccharide, a representative B cell mitogen, because C3H/HeJ spleen cells which are low responders to lipopolysaccharide could respond to mite antigens. These antigens induced not only proliferative response of murine B cells, but also immunoglobulin production. By gel-filtration column chromatography, the active fractions were eluted around the molecular weight of 150-155 kDa. Furthermore, mite antigens also stimulated human B cells to proliferate and to produce immunoglobulin. All these results suggest that mite antigens are a potent B cell mitogen and this activity might concern the induction of allergic reaction.