Mouse Ly-49D recognizes H-2Dd and activates natural killer cell cytotoxicity.

Although activation of natural killer (NK) cytotoxicity is generally inhibited by target major histocompatibility complex (MHC) class I expression, subtle features of NK allorecognition suggest that NK cells possess receptors that are activated by target MHC I. The mouse Ly-49D receptor has been shown to activate NK cytotoxicity, although recognition of MHC class I has not been demonstrated previously. To define Ly-49D-ligand interactions, we transfected the mouse Ly-49D receptor into the rat NK line, RNK-16 (RNK.

DAP12-mediated signal transduction in natural killer cells. A dominant role for the Syk protein-tyrosine kinase.

The murine Ly49 family contains nine genes in two subgroups: the inhibitory receptors (Ly49A, B, C, E, F, G2, and I) and the noninhibitory receptors (Ly49D and H). Unlike their inhibitory counterparts, Ly49D and H do not contain immunoreceptor tyrosine-based inhibitory motifs but associate with a recently described co-receptor, DAP12, to transmit positive signals to natural killer (NK) cells. DAP12 is also expressed in myeloid cells, but the receptors coupled to it there are unknown.

Natural killer cells in the nonpregnant murine uterus.

Recent studies on the origin and function of the large granular cells that accumulate at implantation sites in the rodent uterus during pregnancy have shown that these cells are highly differentiated natural killer (NK) cells. These findings raise questions about the presence and regulation of NK cells in the normal, nonpregnant uterus. For example, do NK cells comprise a major or minor population of leukocytes in the uterus? Are these uterine NK cells (uNK) similar in phenotype and function to NK cells in other organs? Is the population of uNK cells maintained by local proliferation and/or by influx via the blood stream from the bone marrow? This brief review will examine our current understanding of those questions based on the experimental literature on rodents and our own recent studies.

Stage-specific expression of activation antigens on NK cells at uterine implantation sites in mice.

The differentiation of the cellular components of the uterine decidua, in particular the life history of NK cells, is poorly understood. With the use of two mAbs that recognize stage-specific activation Ags on NK cells, we investigated the development of NK cells known as granulated metrial gland (GMG) cells. Immunohistochemical analysis demonstrated that mAb 3C2, but not mAb 4H12, recognized numerous cells throughout the uterine decidua basalis during early gestation.