Identification of an epitope of type 1 streptococcal M protein that is shared with a 43-kDa protein of human myocardium and renal glomeruli.
The localization of opsonic and tissue-cross-reactive epitopes within the amino terminus of type 1 streptococcal M protein was investigated by using murine mAb raised against synthetic peptides of type 1 M protein. Two mAb (IIIA2 and IIIB8) reacted with epitopes located within amino acid residues 1-12 of type 1 M protein. These antibodies opsonized type 1 streptococci and did not cross-react with human kidney and heart tissue. Another mAb (IC7) reacted with mesangial cells of renal glomeruli and human myocardium. The cross-reactive epitope of mAb IC7 was localized to position 13-19, indicating that it is not the same epitope as the previously described vimentin-cross-reactive epitope at position 23-26 of type 1 M protein. In Western blots of mesangial cell and myocardial proteins, mAb IC7 cross-reacted with a 43-kDa protein. Neither vimentin nor actin inhibited the binding of mAb IC7 to the cross-reactive protein, as determined by Western blot or immunofluorescence inhibition tests. These results provide evidence that type 1 M protein contains at least one autoimmune epitope shared with both human glomeruli and myocardium.
Department of Veterans Affairs Medical Center, Memphis, TN 38104.
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W
Kraus
J B
JB
Dale
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EH
Beachey
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D015153:Blotting, Western; D002352:Carrier Proteins; D003429:Cross Reactions; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D005920:Glomerular Mesangium / Q000276:immunology; D006801:Humans; D007678:Kidney Glomerulus / Q000276:immunology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009206:Myocardium / Q000276:immunology*; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D013291:Streptococcus / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000939:Epitopes; D010455:Peptides; C014689:streptococcal M protein