INTERLEUKIN-2 (IL-2) AND INTERFERON-GAMMA PRODUCTION BY LYMPHOCYTES-T FROM PATIENTS WITH B-CHRONIC LYMPHOCYTIC-LEUKEMIA - EVIDENCE THAT NORMALLY RELEASED IL 2 IS ABSORBED BY THE NEOPLASTIC B-CELL POPULATION

Abstract

The capacity of T lymphocytes from patients with B cell chronic lymphocytic leukemia (B-CLL) to release interleukin 2 (IL 2) and interferon (IFN)-.gamma. was assessed following various stimuli. The spontaneous release of IL 2 and IFN-.gamma. was practically absent both with B-CLL and normal T lymphocytes. By contrast, after stimulation with phytohemagglutinin (PHA) or with PHA plus 12-O-tetradecanoylphorbol-13-acetate, the production of IL 2 and IFN-.gamma. by B-CLL T lymphocytes was similar to that of normal T lymphocytes, irrespective of the reversed T lymphocyte subset distribution (OKT4/OKT8 ratio) observed in B-CLL. However, the titer of IL 2 was greatly reduced when autologous leukemic B cells were added to the culture system. Unlike IL 2, the presence of leukemic B cells did not affect the titer of IFN-.gamma. in the culture supernatants. The indication that IL 2 may be adsorbed in vivo by the neoplastic B cells was further confirmed by the demonstration of the IL 2 receptor (revealed by anti-Tac monoclonal antibody) on the leukemic B cells, particularly following mitogenic stimulation, and by the evidence that exogenous IL 2 can be directly absorbed by untreated B-CLL cells. These findings suggest that the ability of B-CLL T lymphocytes to release IFN-.gamma. and IL 2 is preserved, but that IL 2 may be rapidly removed by the neoplastic B-CLL cells, thus contributing to the well-documented T lymphocyte abnormalities present in this disease.