title: The lipopolysaccharide co-receptor CD14 is present and functional in seminal plasma and expressed on spermatozoa.
abstract: CD14 is a 54 000-molecular weight (MW) glycolipid-anchored membrane glycoprotein, expressed on myeloid cells, which functions as a member of the lipopolysaccharide (LPS) receptor complex. Soluble forms of CD14 have been reported in plasma, cerebrospinal fluid, amniotic fluid and breast milk. In plasma and breast milk, soluble CD14 has been implicated as a regulator of T- and B-cell activation and function. Expression of CD14 in the male reproductive system has not previously been investigated. We here show that soluble CD14 is present in seminal plasma at levels comparable to those in serum. Spermatozoa expressed CD14 on their membranes, as demonstrated by fluorescence microscopy and flow cytometry. Post-vasectomy, the levels of seminal plasma CD14 (spCD14) were much reduced, implying an origin distal to the point of transection of the vas deferens. Ultracentrifugation analyses demonstrated that spCD14 was not associated with lipid complexes, indicating that it lacks the glycolipid anchor. Purified spCD14 mediated activation by LPS of CD14-negative cells. These findings suggest that CD14 may play a hitherto unexplored role in immune defence and cell activation in the male reproductive tract.
authors.affiliation: Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, UK.
authors.forename: C L
authors.initials: CL
authors.lastname: Harris
authors.forename: M A
authors.initials: MA
authors.lastname: Vigar
authors.forename: J E
authors.initials: JE
authors.lastname: Rey Nores
authors.forename: V
authors.initials: V
authors.lastname: Horejsi
authors.forename: M O
authors.initials: MO
authors.lastname: Labeta
authors.forename: B P
authors.initials: BP
authors.lastname: Morgan
mesh_terms: D015153:Blotting, Western / Q000379:methods; D002846:Chromatography, Affinity / Q000379:methods; D004731:Endotoxins / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005434:Flow Cytometry; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D008856:Microscopy, Fluorescence; D012661:Semen / Q000276:immunology*; D012995:Solubility; D013094:Spermatozoa / Q000276:immunology*; D014659:Vasectomy
chemical_list: D004731:Endotoxins; D018950:Lipopolysaccharide Receptors