T-cell receptor V beta gene expression in infiltrating cells in murine hearts with acute myocarditis caused by coxsackievirus B3.

BACKGROUND In viral myocarditis, we previously reported that natural killer cells infiltrate the heart first, then activated T cells infiltrate second and play an important role in the pathogenesis of the myocardial damage. METHODS AND RESULTS To elucidate the nature of T-cell infiltration, using a murine model of acute myocarditis caused by coxsackievirus B3, we analyzed the expression of T-cell receptor (TCR) V beta genes in infiltrating cells in the heart by polymerase chain reaction (PCR). The PCR-amplified products were confirmed by Southern blot hybridization with a C beta cDNA probe. In contrast to spleen lymphocytes, the repertoire of V beta gene transcripts in the heart was restricted. The infiltrating cells expressing V beta 10 were found in six of eight hearts of mice with acute myocarditis. The infiltrating cells expressing V beta 8 and V beta 13 were found in four of eight hearts with myocarditis, respectively. Immunoperoxidase staining of serial sections of the heart of myocarditis for TCR alpha beta chains and TCR V beta 10 confirmed that the dominant population of infiltrating T cells expressed V beta 10 gene products. CONCLUSIONS The restricted usage of TCR genes by infiltrating T-cells may indicate that a specific antigen in heart with myocarditis is targeted. Our findings raise the possibility of immunotherapy with monoclonal antibodies specific for TCR V beta elements to prevent T-cell-mediated myocardial damage in viral myocarditis.