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Lipopolysaccharide stimulates alveolar macrophage adherence in vivo and in vitro

J Edelman1, C Cardozo, M Lesser

  • 1Pulmonary Division, Mount Sinai Medical Center, New York, NY 10029.

Agents and Actions
|March 1, 1989
PubMed

Insights

Escherichia coli lipopolysaccharide (LPS) significantly reduces alveolar macrophages (AM) in bronchoalveolar lavage (BAL) samples due to increased AM adherence to lung tissues. Lidocaine lavage partially reverses this LPS-induced effect.

Area of Science:

  • Immunology
  • Pulmonary Medicine
  • Microbiology

Background:

  • Alveolar macrophages (AM) play a crucial role in lung immunity.
  • A decrease in AM count is observed in bronchoalveolar lavage (BAL) following E. coli lipopolysaccharide (LPS) administration.
  • The underlying mechanism for this reduction in AM yield is not fully understood.

Purpose of the Study:

  • To investigate the mechanism behind the decreased number of AM obtained by BAL after LPS infusion.
  • To evaluate the adherence properties of AM from rats treated with LPS compared to normal saline (NS).
  • To determine if LPS directly affects AM adherence.

Main Methods:

  • Rats were intravenously injected with E. coli LPS (3 mg/kg) or NS.
  • Bronchoalveolar lavage (BAL) was performed using normal saline or a 17 mM lidocaine solution (LDC).
  • AM adherence to rotating plastic tubes was measured.
  • Normal AM were incubated with varying concentrations of LPS in serum-free media.

Main Results:

  • BAL samples from LPS-treated rats showed significantly fewer AM (4.09 x 10^6) compared to NS-treated rats (7.55 x 10^6).
  • Lavage with LDC significantly increased AM yield in LPS-treated rats (7.38 x 10^6).
  • AM from LPS-treated rats exhibited significantly greater adherence to plastic surfaces.
  • In vitro incubation with LPS increased AM adherence, with a dose-dependent effect.

Conclusions:

  • The reduced number of AM obtained by BAL in LPS-treated rats is attributed to increased adherence of AM to alveolar structures.
  • This phenomenon is likely mediated by direct effects of LPS on alveolar macrophages.
  • Lidocaine may interfere with LPS-induced AM adherence, suggesting potential therapeutic implications.

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