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Updated: Aug 16, 2026

Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody (mAb) by Neutralizing TNF Using an In Vitro Bioanalytical Method
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Determination of the Relative Potency of an Anti-TNF Monoclonal Antibody (mAb) by Neutralizing TNF Using an In Vitro Bioanalytical Method

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Differences in the tumor necrosis factor-alpha-mediated lysis by fixed natural cytotoxic cells and fixed cytotoxic

W E Vanderslice1, J L Collins

  • 1Washington University School of Medicine, St. Louis, MO 63110.

Journal of Immunology (Baltimore, Md. : 1950)
|January 1, 1991
PubMed

Insights

Natural cytotoxic (NC) cells use cell-associated tumor necrosis factor (TNF) to kill target cells. Unlike macrophages, NC cells lose this activity after fixation, indicating different TNF association mechanisms.

Area of Science:

  • Immunology
  • Cell Biology

Background:

  • Tumor necrosis factor (TNF) is crucial for cytotoxic activity in effector cells.
  • Macrophages utilize cell-associated TNF for lysis, retaining activity even after fixation.

Purpose of the Study:

  • To investigate the role and association of TNF in natural cytotoxic (NC) cell-mediated cytotoxicity.
  • To compare the TNF-mediated cytotoxic mechanisms of NC cells with those of macrophages.

Main Methods:

  • Paraformaldehyde fixation of effector cells.
  • Assessment of cytolytic activity post-fixation.
  • Incubation with LPS and recombinant TNF (rTNF) before fixation.
  • Western blot analysis to detect TNF forms.

Main Results:

  • NC cells use cell-associated TNF for target cell lysis, similar to macrophages.
  • Paraformaldehyde fixation abolishes NC cell cytolytic activity, unlike macrophages.
  • Fixed NC cells showed no enhanced activity with LPS or rTNF pre-incubation.
  • NC cells utilize a smaller, constitutively active 17 kDa form of TNF, distinct from macrophages.

Conclusions:

  • NC cells and macrophages employ cell-associated TNF for cytotoxicity but differ in TNF association.
  • The mechanism of TNF anchoring to the cell membrane differs between NC cells and macrophages.
  • NC cells' cytolytic activity is dependent on a specific, smaller TNF variant and its membrane association.

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