CHARACTERIZATION OF THE CELLS THAT MIGRATE FROM METRIAL GLANDS OF THEPREGNANT MOUSE UTERUS DURING EXPLANT CULTURE

Granulated metrial gland (GMG) cells are estrogen-receptor and Interle ukin 2 (IL-2) receptor positive lymphocytes of the Natural Killer cell lineage found in the murine uterus during pregnancy. Functional studi es of these cells, which are now more frequently called uterine NK (uN K) cells, have been limited due to technical difficulties. The cells a re difficult to isolate and their proliferation and differentiation ha ve not been achieved in culture. In 1988, Mukhtar and Stewart (Cell Ti ss. Res., 253, 413-417) reported a method for explant culture of metri al glands isolated from pregnant rodents that yielded an almost pure p opulation of uNK cells. This major technical advance has supported mos t of the subsequent functional and molecular studies of rodent uNK cel ls. However, the quality of the cells isolated by the explant culture procedure has not been established. A cytochemical approach was used t o identify and quantify the cells migrating from metrial glands. At mi dpregnancy, almost all (> 90%) migrating nucleated cells were NK cells . Earlier in gestation, a significant proportion (25%) of cells having lymphoid morphology could not be assigned to the lineage. The viabili ty of cells migrating from explants was assessed by DNA isolation and electrophoresis on days 6-16 of gestation. At all times evidence for a poptosis was found, even after culture intervals as brief as 4 h. Para llel analyses of histological sections of the metrial gland, using ter minal deoxytransferase labelling to detect nuclear fragmentation, did not support significant levels of uNK cell death in situ prior to day 12 of gestation. Supplementation of the explant culture medium with es trogen, IL-2, various extracellular matrices, decidual cells or combin ations of these did not lead to in vitro proliferation of uNK cells an d usually did not extend the short term viability of these cells in se rum supplemented or serum free media. Thus, the optimal culture condit ions for uNK cells remain undefined. (C) 1997 Elsevier Science Ireland Ltd.