Mitogenic activity of staphylococcal protein A is due to contaminating staphylococcal enterotoxins.
Soluble protein A from S. aureus is widely used as a polyclonal activator of human T cells. However, recombinant protein A produced in E. coli does not show any mitogenic properties, although its IgG-binding activity is identical to protein A purified from S. aureus. Antisera against the staphylococcal enterotoxins A and B are able to specifically inhibit the response of human T lymphocytes to protein A from S. aureus. Therefore, the mitogenic principle of this extensively used T cells activator is due to minute contaminations by enterotoxins that are active in picomolar concentrations.
D002478:Cells, Cultured; D004768:Enterotoxins / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008934:Mitogens; D011994:Recombinant Proteins / Q000494:pharmacology; D013205:Staphylococcal Protein A / Q000494:pharmacology*; D013210:Staphylococcus / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology
D004768:Enterotoxins; D008934:Mitogens; D011994:Recombinant Proteins; D013205:Staphylococcal Protein A