Identification and characterization of a T cell growth inhibitory factor produced by K562 erythromyeloid cells |
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| Authors: | M De Felice H M Bond R Pizzano M C Turco G Valerio A Lamberti P Carandente Giarrusso S Venuta |
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| Affiliation: | Dipartimento di Medicina Sperimentale e Clinica, Facoltà di Medicina, Catanzaro, Italy. |
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| Abstract: | Cells of the human erythroleukemia cell line K562 constitutively secrete a factor that inhibits human T lymphocyte proliferation induced via CD3/Ti. The factor, termed K-TIF (K562-derived T cell inhibitory factor) is produced in either the presence or absence of fetal calf serum in cultures of K562 cells and can be precipitated by 70% NH4SO4. Gel filtration chromatography on Superose 12 resin by FPLC showed that the inhibitory factor has a molecular weight of approximately 30-35 kDa. A protein of this size, metabolically labeled with [35S]methionine, specifically bound human peripheral blood mononuclear cells. Chromatofocusing with Mono P by FPLC (pH gradient 7.2-5) indicates that the inhibitory factor has an isoelectric point of 6.0-6.4. |
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