THERAPEUTIC EFFECT OF NEURAMINIDASE-TREATED LAK CELLS ON LIVER METASTASIS OF COLON-26

To improve the lymphokine-activated killer (LAK) cell therapy for live r metastasis, two methods which enhance accumulation of LAK cells in t he liver were examined for their effects on the liver metastasis of Co lon 26 cancer cells in BALB/c mice. Distribution of LAK cells in the m ice was examined by the Cr-51 labeling method. Portal vein infusion of LAK cells or tail vein infusion of neuraminidase treated-LAK (N-LAK) cells showed an augmented accumulation of infused cells in the liver. In the first experiment, LAK cells (5 x 10(7) cells) were infused in t he portal vein or tail vein at days 3 and 7 after the inoculation of 5 x 10(4) tumor cells and 1 x 10(4) units of IL-2 were given three time s a day from day 3 to day 7. The portal infusion of LAK cells produced a greater reduction of liver metastases compared with the peripheral infusion. In the second experipent, 5 x 10(7) LAK cells or N-LAK cells were infused via the tail vein on days 1 and 3, and 1 x 10(4) units o f IL-2 were given once a day from day 1 to day 5 after the inoculation of 1 x 10(4) tumor cells. The therapeutic effect of N-LAK cells was g reater than non-treated LAK cells on the number of metastatic lesions and the survival time of mice. Since access to the human portal vein i s difficult and risky in clinical situation, peripheral infusion of N- LAK cells is preferable.