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Effect of dexamethasone on B7 regulation and T cell activation in neonates and adults

Thorsten W Orlikowsky1, Günther E Dannecker, Bärbel Spring

  • 1University Children's Hospital, 72070 Tuebingen, Germany. thorsten.orlikowsky@med.uni-tuebingen.de

Pediatric Research
|February 19, 2005
PubMed

Insights

Neonatal macrophages are highly sensitive to dexamethasone, which inhibits their ability to stimulate T cells. This potent effect, while potentially therapeutic, may severely impair immune function in newborns.

Area of Science:

  • Immunology
  • Neonatal Medicine
  • Pharmacology

Background:

  • Dexamethasone's safety in neonates is debated due to its broad immune effects.
  • Specific impacts of dexamethasone on neonatal versus adult macrophage (MPhi) co-stimulatory and suppressive functions remain unclear.

Purpose of the Study:

  • To investigate dexamethasone's effect on B7 family receptor expression (CD80, CD86) in neonatal and adult macrophages.
  • To assess how dexamethasone influences macrophage-mediated T cell co-stimulation and function.

Main Methods:

  • Isolated cord blood macrophages (CBMPhi) and adult peripheral blood macrophages (PBMPhi).
  • Phenotyped cell surface markers using flow cytometry.
  • Exposed cells to dexamethasone, IFN-gamma, cAMP, or alphaCD3 stimulation to evaluate T cell activation and cytotoxicity.

Main Results:

  • Neonatal macrophages showed lower baseline expression of CD80 and CD86 compared to adult macrophages.
  • Dexamethasone significantly inhibited CD80, CD86, and HLA-DR upregulation on both neonatal and adult macrophages, with a more pronounced effect on neonatal cells.
  • Dexamethasone enhanced macrophage-induced T cell cytotoxicity and inhibited T cell CD28 upregulation, effects that were more severe in neonatal macrophages.

Conclusions:

  • Neonatal macrophages exhibit heightened sensitivity to dexamethasone's inhibitory effects on B7 expression.
  • While dexamethasone may offer therapeutic benefits, it risks causing significant impairment of macrophage-dependent T cell functions in newborns.

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