Immune Responses in Humans while Receiving Adoptive Immunotherapy with Recombinant Interleukin-2 and Lymphokine-Activated Killer Cells: Acute Anergy to Mitogens and Recall Antigens

Abstract

In this study we evaluated the in vitro immunologic responses of 11 patients receiving immunotherapy with either interleukin-2 (IL-2, 3 X 10(6) units/m2) or IL-2 plus lymphokine-activated killer cells (LAK) over a 30-day period. Blastogenic responses to mitogens or recall antigens were found to significantly decrease during therapy. Pokeweed mitogen immunoglobulin (Ig) production decreased significantly in 7 patients or showed no change. In vivo skin tests for cell-mediated immunity were also performed and the average number of positive responses before IL-2/LAK therapy decreased to no positive responses (day 29 of therapy). Experiments were performed to determine whether decreased responses were a result of active suppression or a dilution effect by immature/mature cells that cannot respond to mitogen or antigen. Pre-therapy cells were mixed with fresh autologous (anergic) cells from day 29 of therapy in varying ratios. Blastogenesis and Ig production was measured. Our findings demonstrate that the decreased immune response observed during and after therapy is a result not of active immunosuppression but rather of a dilution effect by cells with immune dysfunction. We conclude that: (1) in vitro blastogenesis or Ig production tests using mitogens or antigens for patients undergoing IL-2 immunotherapy have no predictive value, and (2) the immune cells that are present are refractory.