T cells recognize foreign pathogens in the body when fragments of the pathogen, antigenic epitopes, are 'presented' to them by specific molecules, termed major histocompatibility complexes (MHC), on the surface of infected or malignant cells. This interaction activates the T cells, stimulating a multicellular cascade of actions that, ideally, both eliminates the foreign invaders and protects against future incursions. Hence, antigen presentation is an early and essential step in eliciting T cell-mediated immune responses.

Antigen Express technology focuses on modulating immune responses mediated by T helper (Th) cells, a class of lymphocytes that plays a multifaceted role in the immune system, both enhancing and suppressing immune responses. Th cells are essential both for obtaining a robust and long lasting response against infectious agents or cancer cells and for down regulating immune responses when the immune system becomes inappropriately stimulated, e.g. in autoimmune disease and allergy.

The heart of the Antigen Express technology platform is the Ii (invariant chain) protein, which regulates antigen presentation by MHC class II molecules and consequent T helper cell activation. We have established two technology platforms and advanced a number of product-focused projects toward the clinic based on the modulation of expression and use of the Ii protein. The first of these technologies involves suppression of expression of the Ii protein while the second involves the design of Ii 'hybrids', which contain both an MHC class II antigenic epitope and a portion of the Ii protein.

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