Monoclonal antibodies to CD45 modify LPS-induced arachidonic acid metabolism in macrophages

Area of Science:

• Immunology
• Cell Signaling
• Molecular Biology

Background:

• Lipopolysaccharide (LPS) signaling via CD14 activates macrophages, involving src family kinases and leading to cytokine production and arachidonic acid metabolism.
• CD45 protein tyrosine phosphatase (PTPase) is crucial for T-cell signaling, but its role in macrophages remains largely uncharacterized.

Purpose of the Study:

• To investigate the role of CD45 in modulating lipopolysaccharide (LPS)-induced signaling pathways in macrophages.
• To determine if CD45 influences CD14-dependent responses to LPS.

Main Methods:

• Differentiated THP-1 monocytic cells were treated with LPS and monoclonal antibodies (mAbs) or F(ab')(2) fragments against CD45.
• The release of radiolabeled arachidonic acid metabolites, prostaglandin E(2), and tumor necrosis factor alpha was measured.
• Western blots of CD45 immunoprecipitates were used to assess changes in CD45 phosphorylation state.

Main Results:

• Anti-CD45 mAbs and F(ab')(2) fragments enhanced LPS-induced release of arachidonic acid metabolites, prostaglandin E(2), and tumor necrosis factor alpha.
• This enhancement was primarily mediated through CD14-dependent signaling.
• LPS induced a transient alteration in the phosphorylation state of CD45, suggesting a modulation of its enzymatic activity.

Conclusions:

• CD45 plays a significant role in lipopolysaccharide (LPS)-induced responses mediated through the CD14 pathway in macrophages.
• CD45 likely modulates LPS-CD14 signaling possibly via its protein tyrosine phosphatase (PTPase) activity.