Issues

The CEACAM1 protein protects melanoma cells from cytotoxic lymphocytes in vitro via homophilic intercellular interactions. Immunohistochemistry of a human lymph node infiltrated with melanoma cells for CEACAM1 (brown pigmentation) and CD8 (pink pigmentation) showed that almost all CD8-positive lymphocytes in the tumor and its close vicinity were CEACAM1⁺, while most lymphocytes in other areas distant from tumor edge were mostly CEACAM1⁻. This strongly suggests that CEACAM1-mediated inhibition occurs in vivo and thus its blockade is a promising strategy for cancer immunotherapy. For details, see article by Ortenberg and colleagues on page 1300.