Broad-spectrum in-vivo effective superantigen toxin antagonists based on the interaction between cd28 and the superantigen and uses thereof

Abstract

Disclosed are methods and compositions for the inhibition of modulation of T cell costimulatory pathway by a pathogenic agent, particularly, the inhibition of activation of a T cell costimulatory pathway, preferably, the CD28/B7 pathway, by a pyrogenic exotoxin. The method of the invention is based on the inhibition of the direct interaction of a superantigen with a specific site within the dimer interface of a CD28 family member, using immunomodulatory peptides. Further disclosed are specific antagonist immunomodulatory peptides comprising an amino acid sequence derived from a dimer interface of a T cell co-stimulatory pathway member, or peptides which comprise an amino acid sequence which specifically binds to an amino acid sequence within the dimer interface of a T cell co-stimulatory pathway member. Compositions comprising said peptides and methods for the treatment of immune-related disorders are also disclosed. Also disclosed is the use of the CD28 molecule or any fragment thereof comprising the sAg binding site in a method of screening for a test substance which specifically binds to the CD28 molecule and is capable of antagonizing pyrogenic exotoxin-mediated activation of Th1 lymphocytes.