Renal autoimmune epitope of group A streptococci specified by M protein tetrapeptide Ile-Arg-Leu-Arg.
The renal glomerular cross-reactivity of the amino-terminal region of type 1 streptococcal M protein was investigated. Antisera raised in rabbits against a synthetic peptide representing residues 1-26 and a peptide from which residues 20-22 had been omitted during synthesis were capable not only of opsonizing type 1 streptococci but also of reacting in immunofluorescence tests with human renal glomeruli. The cross-reactions were completely inhibited by the immunizing peptides. By using additional synthetic peptides in these inhibition studies, the glomerular cross-reactive epitope was localized to a tetrapeptide sequence Ile-Arg-Leu-Arg at positions 23-26. A number of synthetic M1 peptides containing the tetrapeptide sequence were inhibitory, whereas the M1 peptides lacking the sequence or unrelated tetrapeptides Arg-Gly-Asp-Ser or Arg-Gly-Phe-Ser were without effect. Furthermore, Ile-Arg-Leu-Arg affinity-purified antibodies reacted with renal glomeruli, and the reactivity was inhibited by the tetrapeptide as well as by type 1 M protein. These results indicate that a renal glomerular autoimmune epitope resides in a tetrapeptide Ile-Arg-Leu-Arg near the amino terminus of type 1 streptococcal M protein.
Kraus
W
W
Veterans Administration Medical Center, Memphis, TN 38104.
Beachey
E H
EH
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins; D003429:Cross Reactions; D000939:Epitopes / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007678:Kidney Glomerulus / Q000276:immunology*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000276:immunology*; D010455:Peptides / Q000138:chemical synthesis; D011817:Rabbits / Q000276:immunology; D013297:Streptococcus pyogenes / Q000276:immunology*
D000942:Antigens, Bacterial; D001323:Autoantibodies; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000939:Epitopes; D009842:Oligopeptides; D010455:Peptides; C014689:streptococcal M protein