CD161 molecules, known as NKR-P1, are a family of about 30 kD type II transmembrane C-type lectin-like receptors and are expressed on the cell membrane as disulphide-linked homodimer. Rat NKR-P1 receptors are primarily expressed on NK cells, a subset of T cells, dendritic cells, and activated monocytes. Carbohydrate antigens with GalNac and GlcNac moieties are the ligands for NKR-P1 molecules. CD161 receptors are thought to be involved in the regulation of NK and NKT cell function. Three rat NKR-P1 genes have been described, NKR-P1A, NKR-P1B, NKR-P1B*(or NKR-P1D). 10/78, similar like 3.2.3 antibody, recognizes a common epitope of NKR-1A (CD161a) and NKR-P1B (CD161b). NKR-P1A does not contain ITIM structure and is an activating receptor, while NKR-P1B contains an ITIM and displays an inhibitory function.