Constitutive production of interleukin 1 by human monocytic leukemia cell line JOSK-I and the production mechanism.

JOSK-I is a newly established human monocytic leukemia cell line derived from the peripheral blood of a patient with acute myelomonocytic leukemia. The cells possess immature monocytic features, both cytochemical and immunochemical. It was found that a high level of interleukin 1 (IL-1) was produced by JOSK-I cells without any stimulation. The IL-1 production by JOSK-I cells has the following characteristics: constitutive; cell concentration dependent; and minimal at the logarithmic growth phase and maximal at the saturation density of cell growth. This constitutive production of IL-1 was little affected by the addition of polymyxin B. Partial purification of JOSK-I-derived IL-1 was performed by high-performance liquid chromatography on HPHT hydroxylapatite and TSK gel G3000 SW columns. The activity was found in the molecular weight range of 14,000 to 30,000 and over 70,000. In chromatofocusing, JOSK-1-derived IL-1 exhibited two isoelectric points, pI 6.9 and pI 5.9. Nearly 90% of the activity was immunoprecipitated with rabbit anti-human IL-1 antibody. These characteristics are consistent with those of human monocyte-derived IL-1. This cell line might be an ideal source of native IL-1 for investigating the biological and biochemical characteristics of human IL-1 and its clinical application.