Vascular ligand

Cell-Free Screening on Isolated Vascular Ligands or Receptors... 

Angiopoietins are growth factor ligands of the receptor tyrosine kinase Tie-2 which are critical regulators of vascular assembly and differentiation. 

There may be substantial variation both within and among species (e.g., in mice vs. humans) in the expression of various proteins, receptors and/or ligands that influence the activation of mast cells (or basophils or other potential effector cell types), or that can regulate the responsiveness of end organ target cells (e.g., bronchial or gastrointestinal smooth muscle cells, vascular endothelial cells) to potential mediators of anaphylaxis derived from mast cells. 

Screening the molecular heterogeneity of receptor expression in endothelial cell surfaces is required for the development of vascular-targeted therapies. First, as opposed to targeting purified proteins as discussed above, membrane-bound receptors are more likely to preserve their functional conformation, which can be lost upon purification and immobilization outside the context of intact cells. Moreover, many cell surface receptors require the cell membrane microenvironment to function so that protein-protein interaction may occur. Finally, combinatorial approaches may allow the selection of cell membrane ligands in a functional assay and without any bias about the cellular surface receptor. Therefore, even as yet unidentified receptors may be targeted. 

The major clinical study underpinning product approval was a randomized, double blind study in which 71 CTCL patients were administered the product at one of two dosage levels (9 or 18 [tg kg 1 day ) overall, 30 per cent of patients experienced an objective tumour response. Serious side effects potentially associated with product administration include acute hypersensitivity-type reactions, vascular leak syndrome and visual impairment. Additional adverse reactions include flu-like symptoms, headache, hyper- or hypo-tension, as well as digestive upset. Ontak is manufactured by Seragen Inc. and is distributed by Ligand Pharmaceuticals. 

---