IL-6 undergoes transition from in vitro autocrine growth factor to in vivo growth inhibitor of B lymphoma cells

Dae Ho Cho, Hyung Sik Kang, Jung Jae Ma, Sung Sook Kim, Hwan Mook Kim, Kwang Ho Pyun, Inpyo Choi

Research output: Contribution to journalArticlepeer-review


IL-6 is a multifunctional cytokine involved in differentiation and proliferation of immune cells. Moreover, it has diverse effects on the proliferation of tumor cells in vivo and in vitro. Although stimulating cell growth of multiple myeloma cells, it inhibits the proliferation of B16 melanoma cells and lung cancer cellS. B9.55 cells, B-cell lymphoma, are IL- 6-dependent cells, definitely requiring exogenous IL-6 for growth. When the cDNA for IL-6 was transfected into B9.55 cells, they began growing in an autocrine pattern without exogenous IL-6. To investigate the effects of IL-6 on B9.55 lymphoma in vivo, IL-6-transfected B9.55 cells (B9.G7) or neotransfected B9:55 cells (B9.vec) were injected subcutaneously into syngeneic mice. Initially, B9.G7 outgrew B9.vec, but after 3 weeks, B9.G7 grew slower than B9.vec. In addition, 5 μg of recombinant human IL-6 was injected daily into the tumor site. Reduced tumor sizes of IL-6-treated rats, similar to those observed in mice which received B9.G7, indicated that IL-6 itself is the mediator of tumor regression. When B9.G7 cells were injected into the irradiated normal mice, tumor regression was released compared with the untreated normal control, suggesting that radiosensitive host components were involved in the regression of B9.G7 cell growth. However, the tumor regression of B9.G7 cells was not released in SCID mice. Histologically, B9.G7 tumor demonstrated severe necrosis and apoptotic cells with infiltration of host inflammatory cells. Above data indicate that IL-6 functions as an autocrine growth factor for B9.G7 cells in vitro, but behaves as an autocrine inhibiting factor in vivo. These contrasting effects of IL-6 on tumor cells in vitro and in vivo will be facilitative in understanding the interaction of cytokines and host immune systems.

Original languageEnglish
Pages (from-to)201-207
Number of pages7
JournalJournal of Biomedical Science
Issue number5
Publication statusPublished - 1997
Externally publishedYes


  • Antitumor effects
  • B lymphoma
  • Host immunity
  • IL-6

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology
  • Biochemistry, medical
  • Pharmacology (medical)


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