Inhibiting effects of cancer sera on in vitro responses of peripheral blood lymphocytes to recombinant interleukin-2.

Abstract

The effects of cancer sera on the in vitro induction of lymphokine activated killer (LAK) cells and the killer activity of the LAK cells were determined. When the peripheral blood lymphocytes (PBLs) were incubated with recombinant interleukin-2 in a medium (RPMI 1640 + 10% normal human AB serum) for 96 hours, 53-55% of the LAK activity were induced. LAK induction was inhibited when cancer sera were added to the medium. The inhibition rates varied from slight to high (a mean LAK activity; 37.1%). The cancer sera also inhibited the killer activity of the LAK cells which were already induced in the PBLs. These results suggested the presence of an inhibiting factor against the LAK cells in the cancer serum.