THE CHARACTERISTICS OF THE ACTIVATED KILLER CELLS (AK) INDUCED IN VITRO WITH RECOMBINANT IL-2 (rIL-2)

Abstract

Recombinant IL-2 (rIL-2), secreted from E.Coli harboring a plasmid and containing a synthetic IL-2 gene, is biologically active in inducing activated killer cells (AK) from mouse spleen cells. In this study, we investigeted the biological characteristics of the AK that was induced in vitro by rIL-2. AK were induced by culturing in complete medium containing rIL-2, and recombinant interferon had a synergetic effect with rIL-2. The AK exerted a killer activity on target tumors including P3 myeloma, SP2 myeloma, YAC1 lymphoma, C-26 adenocarcinoma, and BW5147 lymphoma, but not on other targets including Meth-A fibrosarcoma and RL♂lymphoma. The AK were consisted of some heterogenic groups: first Thy1-, asialoGM_^1+ cells which exerted killer activity on YAC1 target; second Thy1+, asialoGM_1+ cells which killed P3, BW5147 and C-26; third Thy1+-, asialoGM_1 cells which revealed broad killer activity on a variety of target tumors including SP2, P3, BW5147 and C-26. Each group of the AK was induced in a different period of cell culture and cold target inhibition test revealed that each had different killer activity on different target determinants. From these findings, it was concluded that the AK induced from mouse spleen cells in the presence of rIL-2 consisted of at least three groups of cells which had different characteristitics with regard to surface markers, target determinants and induction periods.