Objective: Severe combined immunodeficiency (SCID) mice possess neither T nor B lymphocytes and are thus suitable recipients for adoptively transferred lymphocytes. Because autoimmune mechanisms may be involved in the pathogenesis of coxsackievirus B3 (CB3) myocarditis, we attempted to assess the in vitro cellular damage caused by antigen-sensitized lymphocytes and to determine whether splenic lymphocytes from BALB/c mice with chronic CB3 myocarditis could cause myocarditis into SCID mice. Methods and results: Cytotoxic cellular damage against non-myocytes and myocytes was demonstrated using Cr-51-release assay by lymphocytes cultured from myocarditis specimens or splenocytes from mice with chronic CB3 myocarditis. Severe T lymphocyte infiltration with myocardial necrosis was found in adoptively splenocyte-transferred SCID mice, but myocardial necrosis was not defected in wild-type mice by the same procedure. Conclusions: Autoimmune mechanisms might operate in mice with post-CB3 myocarditis and could be transferred in to SCID mice by the antigen-sensitized lymphocytes. An in vivo model of autoimmune post-viral myocarditis in SCID mouse was demonstrated. (C) 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.