Sex-specific effects of Sca-1/Ly-6A on development of B lymphocyte in the bone marrow (P4384)

Abstract Stem cell antigen-1 (Sca-1, also known as Ly-6A) is highly expressed on the hematopoietic stem cells (HSC) and on early lymphoid progenitors, but the role this cell surface protein plays in the development of B cells in the bone marrow is unknown. We report here that the absence of Sca-1/ Ly-6A protein in mice regulates B cell development in the bone marrow in a sex-specific manner. Significant impairment of B cell development was observed in female mice lacking the Sca-1/Ly-6A protein, while this impairment was not observed in Sca-1/Ly-6A deficient males. In contrast, higher percentages of NK1.1+ cells were observed in the thymus from Sca-1/Ly-6A deficient females, while the male mice lacking Sca-1/Ly-6A did not show any alteration when compared to the wild type controls. The deficiency of Sca-1/Ly-6A did not impair development of T cells in the thymus of mice of either sex. These findings indicate that Sca-1/Ly-6A plays an important role in B cell and NK1.1+ cell development and suggests a functional interaction between Sca-1/Ly-6A and female sex hormones in regulating development of B cells and NK1.1+ cells.