Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic

Cancer Immunol Immunother. 2011 Apr;60(4):495-506. doi: 10.1007/s00262-010-0951-9. Epub 2010 Dec 23.


Objectives: IRX-2 is a novel immunotherapeutic containing physiologic quantities of several cytokines which protects human T lymphocytes from tumor-induced or drug-induced apoptosis. Here, we investigate the mechanisms responsible for IRX-2-mediated protection of T lymphocytes exposed to tumor-derived microvesicles (TMV).

Methods: Jurkat cells or primary human T cells ± IRX-2 were co-incubated with TMV and then examined by flow cytometry or Western blots for expression of molecules regulating cell survival (FLIP, Bcl-2, Bcl-xL, Mcl-1) or death (Fas, caspase 8, caspase 9, Bax, Bid). ANX V binding, caspase activation or cytochrome c release were also measured ± cycloheximide (CHX) or ± the Akt-specific inhibitor. Jurkat cells transfected with the cFLIP gene were used to evaluate the role of cFLIP in IRX-2-mediated protection. Effects of CHX on IRX-2-mediated protection and activation of NF-κB upon the TMV/IRX-2 treatment were also measured.

Results: IRX-2 protected T cells from apoptosis by preventing Fas overexpression induced by TMV and blocking caspase 8 activation by up-regulating cFLIP. Jurkat cells overexpressing cFLIP were more resistant to TMV-induced apoptosis than the mock-transfected cells (p < 0.02). Signaling via the PI3K/Akt pathway, IRX-2 corrected the imbalance of pro- versus anti-apoptotic proteins induced by TMV and promoted NF-κB translocation to the nucleus. CHX abolished IRX-2-mediated protection in T cells, suggesting that IRX-2 induces de novo synthesis of one or more proteins that are required for protection.

Conclusions: This biologic may be therapeutically useful for protection of activated T cells from tumor-induced immune suppression and death.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Apoptosis / drug effects
  • Blotting, Western
  • Cell Line
  • Cell Line, Tumor
  • Cell Separation
  • Cytokines / pharmacology*
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Humans
  • Immunotherapy / methods*
  • Jurkat Cells
  • Signal Transduction / drug effects
  • T-Lymphocytes / drug effects*


  • Cytokines
  • IRX 2