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Streptococcus pyogenes type 5 M protein is an antigen, not a superantigen, for human T cells

Lookup NU author(s): Dr Beverley Degnan, Professor John Robinson, Professor Michael Kehoe


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M proteins are coiled-coil dimers expressed on group A streptococcal cell surfaces. They have an important role in host antistreptococcal immunity and in poststreptococcal autoimmune sequelae. Controversy has arisen regarding whether type 5 M proteins are superantigenic for human T cells. To investigate this, we have produced and tested M5 in the form of two novel recombinant proteins. We found no evidence of superantigenicity using either recombinant whole M5 protein (rM5) or recombinant pep M5 protein (rpepM5) to activate peripheral blood mononuclear cells (PBMC) from healthy adult volunteers. Short-term, rM5-specific T-cell lines from different subjects were uniformly self-APC restricted and showed no consistent pattern of TCR Vβ usage. A synthetic peptide of M5 residues 217-237 was found to contain epitope(s) recognized by some rM5-specific human T cells. PBMC responses to rM5 and rpepM5 in 3- and 7-day proliferation assays were characteristic of antigenic rather than superantigenic stimulation. We conclude that type 5 M protein activates human T cells as a conventional antigen.

Publication metadata

Author(s): Degnan B, Taylor J, Hawkes C, O'Shea U, Smith J, Robinson JH, Kehoe MA, Boylston A, Goodacre JA

Publication type: Article

Publication status: Published

Journal: Human Immunology

Year: 1997

Volume: 53

Issue: 2

Pages: 206-215

Print publication date: 01/04/1997

ISSN (print): 0198-8859

ISSN (electronic):

Publisher: Elsevier


DOI: 10.1016/S0198-8859(97)00028-1

PubMed id: 9129980


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