The 10/78 monoclonal antibody recognizes the rat CD161 proteins, CD161a (also known as, Klrb1a, or Nkrp1a/NKR-P1A), and CD161b (Klrb1b, Nkrp1b/NKR-P1B). These type II transmembrane glycoproteins have an extracellular C-type lectin domain and thus belong to the C-type lectin superfamily. These CD161 proteins form ~ 60 kDa homodimers that are expressed on natural killer cells and subsets of T lymphocytes, activated monocytes, and dendritic cells. The 10/78 antibody competes with the previously-described 3.2.3 antibody for binding to these CD161 proteins. CD161 molecules are C-type lectin-like receptors that can either activate (CD161a) or inhibit (CD161b) effector leucocyte responses, eg, cytotoxicity or cytokine production, against target cells which express C-type lectin-like related (Clr) molecules. Although several members of the Klrb1 gene family have been identified in the mouse and rat, only a single human KLRB1 homolog has been discovered.