The induction of LAK cells in the peritoneal cavity of mice by combined treatment with OK-432 and rIL-2

Abstract

In ongoing studies on immunotherapy against peritoneal carcinomatosis, LAK cells were introduced into the peritoneal cavity of mice. Antitumor effects of i. p. treatments of OK-432 and rIL-2 given sequentially were studied. When OK-432 was given in a dose of 1 KE, the number of peritoneal exudate cells (PEC) and the ratio of asialo GM 1 (asGM 1)⁺ cells significantly increased in murine peritoneal cavity and a peak was reached on day 5 after treatment. The mice were then injected i. p. with rIL-2 at a dose of 5×10⁴U. LAK activity of PEC against NK-resistant target cells, EL-4, on day 6 was significantly higher than that in case of PEC with OK-432 alone. In vivo pretreatment of the PEC with anti-asGM 1 antibody prior to rIL-2 eliminated the augmentation of LAK activity. Sequential injection of OK-432 and rIL-2 to mice bearing X 5563 plasmacytoma augmented the LAK activity of PEC and the survival rate of tumor bearing mice was increased. Thus, the in vivo induction of LAK cells by the combined sequential injection of OK-432 and rIL-2 may be given consideration for treating patients with peritoneal carcinomatosis.