Abstract: Methods for quantitatively determining a binding kinetic parameter of a molecular binding interaction, for example wherein the determination involves a complex sample, are provided. Aspects of embodiments of the methods include: producing a magnetic sensor device including a complex sample including a magnetic sensor in contact with an assay mixture including a magnetically labeled molecule to produce a detectable molecular binding interaction; obtaining a real-time signal from the magnetic sensor; and quantitatively determining a binding kinetics parameter of the molecular binding interaction from the real-time signal. Also provided are systems and kits configured for use in the methods.

Abstract: The invention provides a polypeptide sequence, GHIKSSISFMGM, that disrupts binding of the amino acid sequence peptides of myelin basic protein (MBP) to HLA-DR2 class II MHC molecules and acts as an antagonist in DR2-restricted antigen presentation to human T cell clones. In particular, the invention provides the polypeptide sequence itself and variants, compositions comprising the polypeptide, polynucleotides encoding the polypeptide, and methods for using the polypeptides and polynucleotides for treating autoimmune disorders.