Effect of lymphoblastoid interferon on lymphocyte subsets in cancer patients

The effect of interferon dose on lymphocyte subsets is unclear for humans, especially with prolonged intermittent administration. Enumeration of T4 and T8 cells and natural killer (NK) cell activity against K562 cells were examined as part of our ongoing randomized clinical study comparing low- and high-dose treatment strategies. Fifty-four patients have been entered into study, of which 46 are now evaluable. High-dose patients showed no significant changes during actual interferon infusion. However, over the entire period on study, there was a significant increase in NK cell activity (p = 0.001), a concurrent decrease in T8 (p = 0.004), and an increase in T4/T8 (p = 0.02). By contrast, for low-dose patients there was a trend of increasing NK activity during interferon administration, but no change during the total time on study, with a concurrent trend of decreasing T4/T8 and a significant increase in T8 (p = 0.01). Although there is as yet no significant response difference between high- and low-dose treatments, a favourable response was associated with an overall increase in NK activity (p = 0.005), a decrease in T8 (p = 0.02), and an increase in T4/T8 (p = 0.03). In a preliminary study of immune complexes in selected patients, an inverse relationship between NK cell activity and immune complex concentration was suggested. This was supported by in vitro addition of autologous immune complex-containing sera during NK cell assay.