Clone REA1019 recognizes a common epitope of the mouse Ly-49C/F/I/H family members which are single-pass type II C-type lectin-like membrane glycoproteins also known as Ly-49 inhibitory receptors C, F, and I and activating receptor H. It does not react with other Ly-49 members. The Ly-49 receptors are encoded by a family of highly polymorphic and polygenic genes within the mouse NK gene complex which includes genes that encode both inhibitory and activating Ly-49 receptors. Ly-49 receptors recognize MHC-I and MHC-I–like proteins on normal as well as altered cells. They are described as being expressed on both the developing and mature NK cells. The inhibitory Ly-49 receptors are involved in NK cell education, a process in which NK cells acquire function and tolerance toward cells that express “self-MHC-I.” On the other hand, the activating Ly-49 receptors recognize altered cells expressing activating ligands. Ly-49 receptors have been described on multiple NK cell subsets, such as uterine NK and memory NK cells, as well as NKT cells, dendritic cells, plasmacytoid dendritic cells, macrophages, neutrophils, and cells of the adaptive immune system such as activated T cells and regulatory CD8

T cells.