Targeted gene disruption of murine CD7

CD7 is a 40 kDa type I transmembrane glycoprotein member of the Igsuperfamily. CD7 is a marker of mature human T cells and NK cells, and isexpressed early in their development. Cross-linking CD7 positivelymodulates T cell and NK cell activity as measured by calcium fluxes,expression of adhesion molecules, cytokine secretion and proliferation. CD7associates directly with phosphoinositol 3'-kinase, and CD7 ligationinduces production of D-3 phosphoinositides and tyrosine phosphorylation.Severe combined immunodeficiency has been associated with a lack oflymphocyte surface CD7. The CD7 ligand is unknown. The murine CD7 homologis encoded by a single gene on chromosome 11. In order to characterize therole of CD7 in lymphocyte development and function we have eliminated theCD7 gene by targeted disruption. CD7- deficient mice display normalhistology of thymus and spleen, normal lymphocyte populations in primaryand secondary lymphoid tissues, and normal serum Ig levels. Specificantibody responses after immunization with T-dependent and T-independentantigens are equivalent in wild-type and CD7 knockout mice. CD7-deficientlymphocytes respond normally to T cell mitogenic and allogeneic stimuli,and display normal NK cell cytotoxicity.