Treatment with recombinant interleukin 2 and lymphokine-activated killer cells (rIL-2/LAK) has produced a clinical antitumor effect in preliminary human trials. The cytokines gamma-interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and tumor necrosis factor beta (TNF-beta, lymphotoxin) have potent in vitro antitumor activity and some clinical toxicities similar to interleukin 2 (IL-2)/LAK. This study sought to determine whether these cytokines were detectable in sera of IL-2/LAK-treated patients. Ten patients were treated with a protocol of 5-day i.v. rIL-2 bolus priming (10(5) units/kg, every 8 h), followed by 5 daily phereses with harvested lymphocytes cultured in vitro to generate LAK, and 5 days of rIL-2 bolus with infusion of LAK cells. Five patients were treated with a protocol modified to a 3-day rIL-2 prime and 6-day continuous infusion rIL-2 (3 x 10(6) units/m2/day) with infusion of LAK cells. Serum specimens were obtained prior to and 0.5, 2, 3, and 5 h after IL-2 or LAK cell administrations. IFN-gamma was detected by enzyme-linked immunosorbent assay, TNF-alpha by WEHI 164 bioassay or enzyme-linked immunosorbent assay, and TNF-beta by WEHI 164 cell bioassay. During the prime, few patients manifested in vivo detectable serum cytokines: IFN-gamma, three of ten, 5-day prime (1.03 +/- 0.46 ng/ml), and zero of five, 3-day prime; TNF-alpha, one of ten, 5-day prime, and one of three, 3-day prime; TNF-beta, one of ten, 5-day prime. The supernatants of in vitro LAK generation cultures had detectable levels of cytokines at 24 h which increased progressively until culture harvest at Day 4 (IFN-gamma, 2.56 +/- 0.34 ng/ml; TNF-alpha, 356 +/- 110 pg/ml; TNF-beta, 8.2 +/- 4.4 units/ml). The highest levels of in vivo serum cytokines occurred following LAK cell infusion and were more often elevated in patients receiving rIL-2 by bolus than by continuous infusion: IFN-gamma, four of six bolus, zero of three continuous infusion; TNF-alpha, six of six bolus (maximum 679 pg/ml) versus two of three continuous infusion (maximum, 106 pg/ml). LAK cells in vitro responded with cytokine release on stimulation by tumor cell lines (IFN-gamma, 0.88 +/- 0.06 ng/ml; TNF-alpha, 426 +/- 16 pg/ml; TNF-beta, 0.64 +/- 0.06 units/ml). In summary, this preliminary study has detected circulating cytokines in sera of patients receiving IL-2/LAK therapy. The greatest cytokine elevations followed LAK cell infusion.(ABSTRACT TRUNCATED AT 400 WORDS)