title: Human CD4+ T cell clones produce and release nerve growth factor and express high-affinity nerve growth factor receptors.
abstract: BACKGROUND
  Increasing evidence shows that nerve growth factor (NGF) plays a role in the complex and fascinating linkage between the nervous and the immune systems due to its ability to modulate functions of several inflammatory cells.
  
  
  OBJECTIVE
  To investigate NGF receptor expression and NGF production and release by human CD4+ cells clones, which have primary relevance in modulating inflammatory events through their different subsets of functional phenotypes.
  
  
  METHODS
  The expression of NGF and a transmembrane tyrosine kinase (TrkA) was evaluated by immunohistochemistry and flow cytometry analysis in five T(H0), six T(H1), and five T(H2) cell clones derived from human circulating mononuclear blood cells. Moreover, the amount of NGF protein was assessed by measuring the NGF levels in culture supernatants of the T cell clones before stimulation and 48 hours after phytohemagglutinin (PHA) activation by use of an immunoenzymatic assay.
  
  
  RESULTS
  Our data have shown that in unstimulated conditions, human CD4+ T cell clones express both immunoreactivity for NGF and the TrkA NGF receptor irrespective of their cytokine profile. Moreover, T(H1) and T(H2) clones, but not T(H0) clones, secrete NGF in basal conditions. PHA activation induces NGF secretion in T(H0) clones and a significant increase of NGF levels in T(H2) (p < 0.05), but not in T(H1) culture supernatants.
  
  
  CONCLUSIONS
  Results obtained represent the first evidence of TrkA expression and NGF production and release in human CD4+ cell clones and suggest a possible functional role of NGF in modulating the immune and inflammatory network.
authors.affiliation: Institute of Neurobiology, Consiglio Nazionale Richerche, Department of Ophthalmology, University of Rome Tor Vergata, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Lambiase
authors.forename: L
authors.initials: L
authors.lastname: Bracci-Laudiero
authors.forename: S
authors.initials: S
authors.lastname: Bonini
authors.forename: S
authors.initials: S
authors.lastname: Bonini
authors.forename: G
authors.initials: G
authors.lastname: Starace
authors.forename: M M
authors.initials: MM
authors.lastname: D'Elios
authors.forename: M
authors.initials: M
authors.lastname: De Carli
authors.forename: L
authors.initials: L
authors.lastname: Aloe
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002999:Clone Cells; D017077:Culture Media, Conditioned / Q000032:analysis; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000378:metabolism; D009414:Nerve Growth Factors / Q000032:analysis / Q000378:metabolism*; D010835:Phytohemagglutinins / Q000494:pharmacology; D020917:Receptor, trkA / Q000378:metabolism; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D009414:Nerve Growth Factors; D010835:Phytohemagglutinins; D017475:Receptors, Nerve Growth Factor; D020917:Receptor, trkA