TY - JOUR T1 - Increased influx of progenitor B cell subsets in the lung with diverse levels of <em>in-situ</em> proliferation and activation in a murine model of allergic inflammation JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P1014 AU - Konstantinos Samitas AU - Carina Malmhäll AU - Madeleine Rådinger AU - You Lu AU - Tünde Deak AU - Margareta Sjöstrand AU - Jan Lötvall AU - Apostolos Bossios Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P1014.abstract N2 - Introduction: B cells are multifunctional leukocytes that act as regulators of allergic inflammation. They differentiate in the bone marrow (BM) from Haematopoietic Stem Cells via pro-B, pre-B and immature B cells. During airway challenge, effectors cells, i.e. eosinophils, move to the lung in different developmental stages implying local differentiation. It is still unclear if this also applies to B cells.Aim: To determine the numbers and phenotypes of B cell precursors in the lung after allergen exposure and investigate their proliferation and activation status in situ.Methods: Ovalbumin (OVA)-sensitized BALB/c mice were exposed intranasally to OVA or PBS for 5 days. Lung tissue was harvested 24h after final allergen exposure. Cells were stained for markers of B cell differentiation (B220, CD43, IL-7R, BP-1, IgM/IgD, IgE, CD138), chemotaxis (CXCR4), viability/proliferation/apoptosis (7AAD/BrdU/Bax) and direct/indirect activation (CD69/CD40,CD86).Results: Pro-B (B220+/CD43+/BP-1-) and pre-B (B220+/CD43-/BP-1+) progenitors increased in the lung after allergen exposure, showed high rate of proliferation (BrdUhigh) and expressed CXCR4. Pro-B cells exhibited resistance to apoptosis (Bax downregulation), while pre-B cells showed increased expression of functional activation (CD40, CD86) and proliferation in situ (s+G2/M phase).Conclusion: Allergen exposure promotes an influx of specific B cell precursor subsets in the lung with anti-apoptotic characteristics that can proliferate in-situ, migrate and be activated. Our data support the notion of a potential regulatory role of B cell precursors in allergic airway inflammation. ER -