"Cd47 (-/-) mice exhibited depletion of natural killer (NK) precursors in bone marrow consistent with the antiphagocytic function of Cd47. In contrast antisense Cd47 knockdown or gene disruption resulted in a dose dependent accumulation of immature and mature NK cells in spleen. Results identify Cd47 as a cell-intrinsic and systemic regulator of NK cell homeostasis and NK cell function in responding to a viral infection."xsd:string