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Infect. Immun., 01 1995, 51-56, Vol 63, No. 1
Z Yang, CD Carter, MS Miller and PN Bochsler
The membrane-associated CD14 receptor (mCD14) is a monocyte/macrophage
differentiation antigen, and it has been demonstrated to serve as a
receptor for bacterial lipopolysaccharide (LPS; endotoxin). Binding of LPS
to mCD14 has been shown to be associated with LPS-induced macrophage,
monocyte, and neutrophil activation in humans. In this report, we describe
the presence and function of an mCD14-like receptor on bovine alveolar
macrophages (bAM). An immunofluorescence technique and flow cytometric
analysis indicated binding of anti-human CD14 monoclonal antibodies (MAb)
My4, 3C10, and 60bd to bAM. Binding of anti- CD14 MAb (3C10 and MY4) was
reduced over 20% by pretreatment of bAM with phosphatidylinositol-specific
phospholipase C (0.5 to 1.0 U/ml), indicating that bovine mCD14 is a
glycosyl phosphatidylinositol- anchored protein. In addition, pretreatment
of bAM with anti-CD14 MAb decreased binding of 125I-labeled LPS to
macrophages, suggesting that bovine mCD14 serves as a receptor for LPS. A
cDNA probe based on the human sequence for CD14 was used in Northern (RNA)
blot analysis, and hybridization to human monocyte CD14 yielded the
expected 1.5-kb band. Hybridization to bovine mRNA yielded a 1.5-kb band
plus an unexpected 3.1-kb band. Constitutive expression of bovine CD14 mRNA
was observed, and the expression level was modestly elevated in bAM
stimulated for 24 h with LPS (1 ng/ml) in the presence of bovine serum. The
function and activation of bAM were assessed by quantitation of tissue
factor (TF) expression on the cells using an activated factor X-related
chromogenic assay and S-2222 substrate. LPS (1 ng/ml)-mediated upregulation
of TF expression on bAM was dependent on the presence of bovine serum
components, and TF expression was inhibited by anti-CD14 MAb. In addition,
TF mRNA levels in LPS-stimulated bAM were decreased by pretreatment of
cells with anti-CD14 MAb (MAb 60bd, 10 micrograms/ml).
Copyright © 1995, American Society for Microbiology
CD14 and tissue factor expression by bacterial lipopolysaccharide- stimulated bovine alveolar macrophages in vitro
Department of Pathology, University of Tennessee College of Veterinary Medicine, Knoxville 37901-1071.
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