Detection of regulatory factors of lymphokine-activated killer cell activity in head and neck cancer patients treated with interleukin-2 and interferon alpha

Interleukin-2 (IL-2) and interferon-α (INF-α) are biologic modifiers that have met with limited clinical success in the treatment of human malignancies. We conducted a phase 2 trial of IL-2-IFN-α in patients with advanced or unresectable squamous cell carcinoma of the upper aerodigestive tract. Two patients were analyzed sequentially for serum induction phase-blocking factors of lymphokine-activated killer (LAK) cell activity in their therapy. Serum also modulated LAK activity independent of autologous or allogeneic effector cells. Significantly inhibitory serum samples were stable in multiple freezings and thawings. Heat-treating the inhibitory serum, at 56°C for 30 minutes, only partially removed the serum inhibitory capacity. Sequential analysis of p55 and p75, subunits of IL-2 receptors, showed that absence of effector cell lytic activity was associated with markedly decreased fluorescence of the IL-2Rp75 subunit only. No significant alteration of the IL-2Rp55 subunit occurred with therapy. These studies support the theory that lymphocyte and multiple serum factors, developing during IL-2-IFN-α therapy, regulate the induction of in vitro LAK activity. Further understanding of these factors may lead to improvements in biologic modifier therapy.