4‐1BB T‐cell antigen binds to mature B cells and macrophages, and costimulates anti‐μ‐primed splenic B cells

Karen E. Pollok, Young‐June ‐J Kim, José Hurtado, Zhen Zhou, Kack K. Kim, Byoung S. Kwon

Research output: Contribution to journalArticle

194 Scopus citations


4-1BB is expressed on activated murine T cells and may function as an accessory signaling molecule during T-cell activation. To identify putative 4-1BB ligands, a fusion protein consisting of the extracellular domain of 4-1BB fused to human placental alkaline phosphatase (4-1BB-AP) was constructed. Alkaline phosphatase activity could then be used as an indicator of the relative amount of bound 4-1BB. These studies indicated that 4-1BB-AP specifically bound to the surface of various mature B and macrophage cell lines. 4-1BB-AP bound at low levels to T cell lines (non-activated and anti-CD3-activated), pre-B-cell lines, and an immature macrophage cell line. 4-1BB-AP did not bind to a glial tumor cell line, HeLa cells, or COS cells. In addition, 4-LBB-AP bound at higher levels to F(ab')2 anti-μ activated primary B cells compared to anti-CD3-activated primary T cells. Scatchard analysis indicated that the A20 B cell lymphoma expressed 3680 binding sites per cell with a K(d) of 1.86 nM. Affinity cross-linking studies demonstrated that a major cell surface species of 120 kDa bound to 4-1BB-AP; 4-1BB-AP also bound to a minor species of approximately 60 kDa. The addition of paraformaldehyde-fixed SF21 cells expressing recombinant 4-1BB synergized with F(ab')2 anti-μ in inducing splenic B cell proliferation suggesting that 4-1BB may function as a regulator of B cell growth.

Original languageEnglish (US)
Pages (from-to)367-374
Number of pages8
JournalEuropean Journal of Immunology
Issue number2
StatePublished - Feb 1994


  • 4-1BB
  • Adhesion molecules
  • B lymphocyte
  • Macrophage
  • T lymphocyte

ASJC Scopus subject areas

  • Immunology

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