Induction by interleukin-7 of lymphokine-activated killer activity in lymphocytes from autologous and syngeneic marrow transplant recipients before and after systemic interleukin-2 therapy.

Therapy with recombinant lymphokines after autologous bone marrow transplantation (ABMT) is being explored as a way to prevent relapse. Lymphokine therapy may exert an antitumor effect through a variety of mechanisms, including the induction of lymphokine-activated killer (LAK) cell cytotoxicity. We tested the ability of interleukin-7 (IL-7) to induce LAK cytotoxicity in peripheral blood mononuclear cells (PBMC) from healthy subjects and from patients early after ABMT. LAK activity was defined as lysis of Daudi by PBMC after incubation with IL-7 at 10 to 100 ng/mL or IL-2 at 1000 U/mL. PBMC from four healthy subjects were cultured with either IL-7 or IL-2. IL-7 induced LAK activity in two of the four, whereas IL-2 induced LAK activity in all four. The median percent lysis (effector-to-target ratio [E:T] 40:1) with IL-7 (23%) was lower than with IL-2 (67%). PBMC were obtained from 15 patients 27 to 84 days after autologous (n = 13) or syngeneic (n = 2) bone marrow transplantation (BMT) and tested for IL-7-induced LAK activity. Eleven exhibited significant activity (10% to 77% lysis at E:T 40:1). In contrast to the results in PBMC from normal subjects, in PBMC from ABMT patients IL-7 induced LAK activity of a magnitude similar to that induced by IL-2. Studies were also performed on PBMC from eight patients who had received IL-2 after ABMT (3.0 x 10(6) U/m2/d) for 4 days by continuous intravenous (IV) infusion. In seven of the eight patients, IL-7 induced significant LAK activity, which was higher than that seen in PBMC from ABMT patients who had not received IL-2. Thus, IL-7 reproducibly induced significant LAK activity in cells obtained early after autologous or syngeneic BMT. Indeed, such LAK activity was comparable quantitatively to that induced by IL-2. Finally, IL-7 induced an even greater LAK activity in vitro in PBMC obtained after ABMT and preactivated in vivo by IL-2 therapy. The results suggest that IL-7 may have a potential immunotherapeutic role, alone or with IL-2, after ABMT.