The cell line was established from primary cultures of adherent cells from Atlantic salmon head kidney. The cells have been used in the study of the infectious salmon anaemia (ISA) virus. SHK-1 cells are recognised by MAbs specific for Atlantic salmon peripheral blood leucocytes, but not with Mabs specific with polymorphonuclear leucocytes. SHK-1 cells have been shown to phagocytose the fish pathogen Aeromonas salmonicidia to some extent, but no bacterical activity was observed over a period of 72 hours. From these results it has been concluded that SHK-1 is derived from leucocytes with some of the properties of macrophages. Studies have shown that the cells can be passaged more than 60 times.