HUMAN-IGG MONOCLONAL-ANTIBODIES THAT MODULATE THE BINDING OF SPECIFICIGE TO BIRCH POLLEN BET-V-1

Birch pollen allergy is a very frequent pathology in Europe and North America. More than 95% of the tree pollen allergic patients display Ig E reactivity against Bet v 1, the major birch pollen allergen. Startin g with PBL from a patient desensitized by immunotherapy, we have gener ated five B cell lines (BAB1 to BAB5) that secrete human IgG mAbs of h igh affinity for Bet v 1. Although competition studies indicated that these human IgG mAb recognized different epitopes, broad cross-reactiv ity was found with Bet v 1 homologous allergens present in tree pollen s and plant-derived foods. When tested for interference with allergic patients' IgE, BAB1 inhibited (by 80-100%) the binding of IgE to nitro cellulose-blotted Bet v 1, while BAB2 enhanced it. The biologic signif icance of the ability of BAB1 to interfere with patients' IgE binding is indicated by the finding that BAB1 completely inhibited Bet v 1-ind uced histamine release from allergic patients' basophils. Allergen-spe cific human IgG mAbs such as BAB1, which presents high blocking activi ty in both immunochemical and cellular IgE competition experiments, mi ght have therapeutical application.