Antibody dependent cytolysis of K-562 cells in the absence of complement or effector cells

The detrimental effect of specific antibody on the K-562 cells is evident in several cellular processes. K-562 human leukemia cells grown in the presence of specific goat anti-K-562 gamma globulins die and are lysed within two to five days. There is a decrease in DNA and protein synthesis and a loss of cell viability within several hours. These events occurred in the absence of added effector cells or complement. The inhibition of DNA synthesis and cytolysis was shown with F(ab')₂, Fab', or Fab as well as with intact immunoglobulin. The effects on the cell was not due to proteolytic, or other external lytic activity generated at the cell surface since Cr labeled bystander cells (Srbc or K-562 cells) were not lysed when added to cultures of K-562 cells incubated with immune gamma globulins. Likewise, the synthesis or activation of complement in K-562 cells was ruled out as being responsible for cytolysis since antibody sensitized bystander cells were not lysed when added to the cultures. An increase in the media concentration of glucose, succinate, or malate did not decrease the effects of the antibody on the K-562 cells. There was no change in the levels of the cyclic nucleotides as a function of incubation with the goat gamma globulins.

The anti-K-562 gamma globulins were not observed to patch or cap on K-562 cells for 24 hours but the ability of bound immuno-globulin to fix complement decreased markedly (50% in 60 minutes) so that no complement-mediated cytolysis could be observed at two hours. Although this loss in the ability to fix complement suggested that antibody may have disappeared from the cell surface, the immunoglobulin, or at least part of it, reacted with fluorescein labeled rabbit anti goat gamma gloublin for at least 24 hours. The ¹²⁵I-labeled Fab, while being released more quickly than whole Ig, was released intact.