Lymphotoxin beta (LTbeta), a member of the tumor necrosis factor family, plays an important role in lymphoid organogenesis. In order to determine whether LTbeta is involved in cellular immunity, we investigated the antiviral immune response of LTbeta-deficient (LTbeta -/-) mice to lymphocytic choriomeningitis virus (LCMV). Cytotoxic T lymphocyte (CTL) responses to LCMV were severely diminished, leading to viral persistence in brain and kidney. However, major functions of LTbeta-deficient T lymphocytes and dendritic cells were intact. Reconstitution of irradiated LTbeta +/+ mice with LTbeta -/- bone marrow induced a disorganized splenic structure, accompanied by impairment of the LCMV-specific CTL response. These data indicate that the absence of LTbeta does not affect the intrinsic function of T lymphocytes or of dendritic cells but that the structural integrity of the spleen is strongly associated with generation of antiviral immunity.