Cell surface markers of the canine natural killer (NK) cell

Studies were performed to determine which of several cell surface markers are expressed on canine peripheral blood leukocyte (PBL) natural killer (NK) cells. Chromium-51 release assays showed a decrease in NK activity after depletion of PBL by carbonyl iron ingestion and adherence to IgG-antibody-coated ovine erythrocytes (EA gamma) and to IgM-antibody-complement-coated ovine erythrocytes (EA mu C). Effector cell adherence to and subsequent lysis of canine thyroid adenocarcinoma (CTAC) target cell monolayers provided direct visual identification of the putative canine NK cell. These surface immunoglobulin-negative cells, individually identified by their physical adherence to dead CTAC target cells, failed to form nonimmune rosettes with guinea pig erythrocytes or rosettes with EA mu or EA mu C. However, 39.0 +/- 4.2% of these adherent cells formed rosettes with EA gamma and 73.3 +/- 0.8% expressed the canine T-lymphocyte marker, Thy-1.