Wasp Venom Rush Immunotherapy Induces Transient Downregulation Of B Cell Surface Molecule Expression

Background: Little is known about the involvement of B cells in venom immunotherapy (VIT). To elucidate changes in the B cell phenotype during this process, we examined the expression of several surface molecules on peripheral B cells before and during VIT. Methods: 15 venom-allergic patients with a history of systemic reactions after a wasp sting and venom-specific skin test reactivity as well as serum IgE were investigated before VIT (day 1), 1 day after reaching a maintenance dose of 100 mug (day 6) during inpatient rush VIT, and again on day 26 during continued outpatient maintenance therapy. Changes in the serum levels of total IgE, allergenspecific IgE (sIgE) and sIgG4 were measured by ELISA. Expression of several surface molecules on doublelabelled B cells was studied by flow cytometry of peripheral blood mononuclear cells. Results: Levels of total IgE, sIgE and sIgG4 showed a significant increase after 26 days of VIT. On day 6, cell surface expression of HLA- II-DR, CD5, CD32 and CD54 was decreased in intensity and numbers of positive cells compared to day 1, while on day 26, expression of these molecules approached again baseline levels. Furthermore, a trend to decreased CD23 was noted on day 6. No changes were observed for CD40, CD86, CD95 and HLA-1-ABC. Conclusion: These data show that during initiation of rush VIT, B cell expression of surface molecules involved in T-B cell cooperation and antigen presentation is downmodulated. B cells may thus be additional direct or indirect targets of highdose antigen therapy and contribute to the persistence of TH1 responses during maintenance VIT treatment. Copyright (C) 2002 S. Karger AG, Basel.