Receptor on the surface of activated T-cells: ACT-4

Abstract

The invention provides purified ACT-4 receptor polypeptides, antibodies against these polypeptides and nucleic acids encoding ACT-4 receptor polypeptides. Also provided are methods of diagnosis and treatment using the same. ACT-4 receptors are preferentially expressed on the surface of activated CD4 + T-cells. ACT-4 receptors are usually expressed at low levels on the surface of activated CD8 + cells, and are usually substantially absent on resting T-cells, and on monocytes and B-cells (resting or activated). An exemplary ACT-4 receptor, termed ACT-4-h-1, has a signal sequence, an extracellular domain comprising three disulfide-bonded intrachain loops, a transmembrane domain, and an intracellular domain.

What is claimed is:  
     
         1 . An antibody, or fragment thereof, that specifically binds an ACT-4-h-1 receptor, wherein said antibody or antibody fragment has a different binding specificity than that of a monoclonal antibody generated by hybridoma HBL106, deposited under ATCC Accession No. HB11483.