Effect of mite antigens on antigen presenting cells/macrophages in mice

The effect of mite antigens on murine lymphocytes and macrophages was studied in vitro. Antigens prepared from Dermatophagoides farinae bodies (Dfb) or recombinant Mag3, glutathione-S transferase (GST)-fused mite antigen, stimulated murine spleen cells to proliferate. The responder cells were B cells, because the response was sensitive to anti-Ig antibody and C treatment, but not to anti-Thy 1 antibody and C treatment. The response was not due to lipopolysaccharide contamination, a representative B-cell mitogen, because polymyxin B column-passed Dfb significantly stimulated B cells, and GST protein alone did not stimulate them. Alloantigen presenting activity was increased in mite antigen-treated B cells and spleen adherent cells. Mite antigens stimulated CD80 and the major histocompatibility complex (MHC) class II molecule expression, but suppressed CD86 expression on B cells and spleen adherent cells that were detected by a flow cytofluorometer. Antibodies to the MHC class II molecules, CD80 and CD86 blocked the alloantigen-presenting activity. Furthermore, mite antigens stimulated B cells and spleen adherent cells to produce cytokines. These results suggest that mite antigens have a stimulating activity on antigen-presenting cells/macrophages and modulate immune responses.