Identification and characterization of a T cell growth inhibitory factor produced by K562 erythromyeloid cells.
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.
De Felice
M
M
Dipartimento di Medicina Sperimentale e Clinica, Facoltà di Medicina, Catanzaro, Italy.
Bond
H M
HM
Pizzano
R
R
Turco
M C
MC
Valerio
G
G
Lamberti
A
A
Carandente Giarrusso
P
P
Venuta
S
S
D006801:Humans; D007526:Isoelectric Point; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000187:drug effects; D008970:Molecular Weight; D013491:Suppressor Factors, Immunologic / Q000302:isolation & purification* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects; D014407:Tumor Cells, Cultured
D013491:Suppressor Factors, Immunologic