Accumulation of immunomodulatory laminaran [beta(1,3)-D-glucan] in the spleen and kidney of Atlantic salmon, Salmo salar L

The tissue distribution of H-3- and FITC-laminaran in Atlantic salmon, Salmo salar L., was investigated after intravenous administration. Liquid scintillation counting and whole-body autoradiography revealed that the concentration of H-3-labelled laminaran in the spleen and anterior kidney was higher than in blood throughout the experimental period (1 h to 12 days). Renal excretion and intestinal exsorption were the main elimination pathways for laminaran. Microscopic examination revealed accumulation of FITC-labelled laminaran in macrophages in kidney and spleen. In addition, endothelial cells in the kidney, spleen, liver and intestine contained the immunomodulator. Thus, these experiments show that laminaran accumulates and is retained in immunologically relevant cells in the kidney and spleen.