Immunophenotypic characterization of peripheral B cells. During short-term immunotherapy with tree pollen allergoid and the immunoadjuvant monophosphoryl lipid A.

The effects of immunotherapy (IT) on the activation and functions of B cells are not well described yet. We therefore measured the expression of several surface markers on peripheral B cells during short-term IT. Twelve patients with seasonal allergic rhinoconjunctivitis, sensitized to hazel, alder, and birch pollen proven by positive history, skin test, sIgE, and nasal provocation test, were included in the study. Eight patients received short-term IT with TA tree pollen and the immunoadjuvant monophosphoryl Lipid A; 4 patients received a placebo suspension containing 2% tyrosine. After separation of PBMCs, the expression of surface molecules on peripheral B cells were analyzed by flow cytometry before the start of IT, before the 3rd injection, at the end of IT, and after the pollen season. The expression of CD23, CD54, and HLA-DR-II on CD19+ B cells decreased during IT and then increased again after the pollen season. In the placebo group, the expression of CD23, CD54, and HLA-DR-II remained unchanged during the first three measurements. After the season, the expression of CD23, CD54 and HLA-DR-II increased in both groups. CD86 expression was decreased during treatment in both groups. Although CD86 expression increased in both groups after the season, the increase was more pronounced in the placebo group. No changes in the expression of CD32, CD40, and HLA-ABC-I were registered during the study. The results show that expression of CD23, CD54, and HLA-DR-II on peripheral B cells decreases during IT, which indicates reduced B-cell activation. Whether these effects are a result of direct allergen action on the B cells or whether they are mediated by T cells and their clinical relevance remains to be elucidated.