THE IMMUNOMODULATORY EFFECT OF LAMINARAN [BETA(1,3)-D-GLUCAN] ON ATLANTIC SALMON, SALMO-SALAR L, ANTERIOR KIDNEY LEUKOCYTES AFTER INTRAPERITONEAL, PERORAL AND PERANAL ADMINISTRATION

Anterior kidney leucocytes obtained from Atlantic salmon, Salmo salar L., 2 days after administration of laminaran, were assayed for their c apacity to reduce nitroblue tetrazolium to formazan, and for their act ivity of lysosomal acid phosphatase after intraperitoneal (15 mg kg(-1 )), peroral (150 mg kg(-1)) or peranal (150 mg kg(-1)) administration. Leucocytes obtained from salmon treated by an intraperitoneal injecti on of laminaran produced significantly more superoxide anion than cell s obtained from fish treated with dextran or sodium chloride immediate ly after cell isolation. Immediately after extraction, the activity of acid phosphatase in anterior kidney leucocytes obtained from salmon i njected with laminaran was significantly higher than in cells harveste d from fish treated with dextran or sodium chloride. Furthermore, cell s obtained from salmon treated by peroral instillation of laminaran sh owed significantly enhanced production of superoxide anion compared wi th leucocytes from fish treated with either sodium chloride or dextran . The acid phosphatase activity in anterior kidney leucocytes from sal mon treated by peroral and peranal instillation of laminaran was signi ficantly higher than in cells from fish treated either with sodium chl oride or dextran. Finally, fluorescence microscopic examination of tis sue sections from fish treated peranally by intubation with fluorescei n labelled laminaran revealed fluorescent vesicles in intestinal epith elial cells and in anterior kidney macrophages.