T-CELLS WITH SIMILAR T-CELL RECEPTOR BETA-CHAIN COMPLEMENTARITY-DETERMINING REGION 3 MOTIFS INFILTRATE INFLAMMATORY LESIONS OF SYNTHETIC PEPTIDES INDUCING RAT AUTOIMMUNE MYOCARDITIS

Experimental autoimmune myocarditis (EAM) resembles the giant cell myo carditis seen in humans, and recurrent forms lead to dilated cardiomyo pathy, EAM has been shown to be a T cell-mediated autoimmune myocardit is. We have previously shown that cDNA encoding V beta complementarity -determining region (CDR) 3 from heart-and pericardial space-infiltrat ing T cells in EAM induced by rod cardiac myosin contains more restric ted sequences than that from normal spleen T cells. Recently, it has b ecome apparent that several epitopes of EAM exist in rod cardiac myosi n; therefore, T cells infiltrating into lesions may recognize certain epitopes in EAM induced by rod cardiac myosin. In this study, we exami ned heart-and pericardial space-infiltrating T-cell clonotypes in EAM induced by synthetic peptides of cardiac myosin. EAM was produced by i mmunization with synthetic peptides corresponding to N-terminally acet ylated amino acids 1539 to 1555 of rat cardiac myosin alpha heavy chai n. Five of 12 rats receiving synthetic peptides developed macroscopic signs of myocarditis, To examine T-cell receptor (TCR) V beta expressi on and CDR3 of the TCR beta chain of lesion-infiltrating T cells in EA M, total RNA was isolated from heart, pericardial effusion, spleen, ly mph node, and peripheral blood. TCR V beta expression of the T cells i nfiltrating the lesions revealed a predominance of V beta 4, On the ba sis of single-strand conformation polymorphism analysis for CDR3 of th e TCR V beta 4 chain, heart-and pericardial space-infiltrating T cells were considered to be oligoclonal, whereas spleen, lymph node, and pe ripheral blood in a rat with EAM and spleen in a native rat were consi dered to be polyclonal, In the same rat, clonotypes of heart-infiltrat ing T cells were almost the same as those of pericardial space-infiltr ating T cells. Furthermore, on sequence analysis for CDR3 of the TCR V beta 4 chain, the amino acid motifs were similar among T cells infilt rating into lesions of different EAM rats. In the present study, TCR b eta chains of heart-and pericardial space-infiltrating T cells in EAM induced by synthesized peptide consisting of 17 amino acids were exami ned. V beta 4+ T cells with similar V beta CDR3 motifs that infiltrate the heart and pericardial space may recognize the same epitope.