Partial purification of an immunosuppressive protein from a human tumor cell line and analysis of its relationship to transforming growth factor beta.
The A673 human rhabdomyosarcoma cell line constitutively produces an acid-soluble, potent immunosuppressive factor (ISF), which inhibits T-cell proliferation. We have partially purified this factor from the culture supernatant of A673 cells by a sequence of acid extraction, gel filtration, cation exchange chromatography, and reverse-phase HPLC. Characterization studies indicate that ISF is similar or identical to transforming growth factor beta (TGF beta). ISF exhibits a molecular weight of 25 kDa in sodium dodecyl sulfate-polyacrylamide gels. ISF, like TGF beta, is a very basic protein (pI = 9.5) that is sensitive to reduction. Anti-TGF beta 1 antibodies completely block ISF activity in the thymocyte assay. Furthermore, ISF, like TGF beta, stimulated the anchorage-independent growth of normal rat kidney fibroblasts in soft agar.
Romeo
D S
DS
Department of Microbiology and Immunology, Wake Forest University Medical Center, Winston-Salem, North Carolina 27103.
Mizel
S B
SB
D000937:Antigen-Antibody Reactions; D001681:Biological Assay; D002845:Chromatography / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D007526:Isoelectric Point; D008213:Lymphocyte Activation; D010835:Phytohemagglutinins / Q000494:pharmacology; D013491:Suppressor Factors, Immunologic / Q000276:immunology / Q000302:isolation & purification*; D015291:Transforming Growth Factors / Q000276:immunology / Q000502:physiology; D014407:Tumor Cells, Cultured
D007375:Interleukin-1; D010835:Phytohemagglutinins; D013491:Suppressor Factors, Immunologic; D015291:Transforming Growth Factors