Indium In 111 Daclizumab

**Semantic type:** Amino Acid, Peptide, or Protein|Pharmacologic Substance

**Definition:** A radioimmunoconjugate comprised of daclizumab, a recombinant humanized monoclonal antibody directed against the alpha subunit of the interleukin-2 (IL-2) receptor (IL-2RA, TAC antigen, CD25), which is labeled with the gamma-emitting isotope indium 111 (In 111; 111In), with potential radioimaging application. Upon administration, indium In 111 daclizumab targets and binds to IL-2RA and inhibits the binding of IL-2, thereby blocking IL-2-mediated activation of lymphocytes. IL-2RA is not expressed by normal resting lymphoid cells, with the exception of regulatory T-cells (Tregs), but it is expressed on a minority of Reed-Sternberg cells and, is overexpressed on T-cells rosetting around Reed-Sternberg cells in certain lymphomas. The use of gamma scintigraphy permits the immunodetection of IL-2RA expressing cells.

**Synonyms:** - In-111-Daclizumab - In111 Daclizumab - In111 MoAb Anti-TAC - MOAB TAC-111IN