CEACAM1 staining of decidual lymphocytes. Decidual lymphocytes were isolated and quadruple-stained as described in Methods. (a–c) CEACAM1 staining on nonactivated decidual NK cells (a), T cells (b), and NKT cells (c). One representative experiment is shown out of three performed. Decidual lymphocytes were cultured in the presence of IL-2 as described (20) and then screened for CEACAM1 expression with the 5F4 mAb. (d–f) CEACAM1 staining for activated decidual NK clone (d), T clone (e), and NKT clone (f). Similar results were obtained when other lymphocyte clones were used. (g and h) Staining of EVTs for HLA-G and CEACAM1, respectively. Bold lines represent mAb staining and thin lines show background staining.