Intensification of host's immunity by squalene in sarcoma 180 bearing ICR mice

Effect of highly purified squalene (HP-SQ) obtained from liver of a shark, Centrophorus atromarginative Garman, on antitumor activity and host's immune response was studied in sarcoma 180 bearing female ICR mice. HP-SQ was administered intraperitoneally (i.p.) to solid tumor-bearing or healthy mice at the dose of 0.1 ml/mouse/d for consecutive 10 d. The administration of HP-SQ exerted the host's resistance against challenging 5 x 10(4) cells of ascites sarcoma 180, and it resulted in marked prolongation of survival of the mice (ILS; 110%). Function of the reticuloendothelial system estimated by a carbon clearance test was enhanced by i.p. administration of HP-SQ in both the healthy and the tumor-bearing mice. Number of IgM antibody forming cells against sheep red blood cells (SRBC) in the spleen was counted 4 d after intravenous injection of 2 x 10(7) cells of SRBC. The number of the IgM antibody forming cell increased by HP-SQ administration in the tumor-bearing and the healthy mice. Delayed hypersensitivity reaction against SRBC measuring swelling of the foot pads of mice was also stimulated by the i.p. administration of the material.