title: Altered plasma nerve growth factor-like immunoreactivity and nerve growth factor-receptor expression in human old age.
abstract: BACKGROUND
  Nerve growth factor (NGF), discovered because of its action on cells in the peripheral and the central nervous system, is now known to act also on immune cells in developing and adult subjects. Whether peripheral lymphocytes of aged subjects are responsive to this molecule is less clear.
  
  
  OBJECTIVE
  Aim of our study was to investigate whether or not plasma NGF undergoes any significant changes during aging and whether or not NGF receptors on peripheral lymphocytes are affected in old subjects.
  
  
  METHODS
  To address these questions, we used RT-PCR, immunohistochemistry, and immunoenzymatic analysis to evaluate the expression of NGF receptors in human peripheral lymphocytes and NGF-like immunoreactivity.
  
  
  RESULTS
  These results revealed a low amount of NGF in the plasma of old subjects associated with a reduced expression of mRNA for NGF receptor trkA in peripheral lymphocytes. They also showed elevated levels of circulating interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) in the bloodstream of adult and aged subjects.
  
  
  CONCLUSIONS
  Our data indicate that peripheral lymphocytes are targets for circulating NGF and suggest that changes in NGF-receptor expression on lymphocytes might be potential marker for aging lymphocytes.
authors.affiliation: Institute of Neurobiology, CNR Rome, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Antonelli
authors.forename: L
authors.initials: L
authors.lastname: Bracci-Laudiero
authors.forename: L
authors.initials: L
authors.lastname: Aloe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D002352:Carrier Proteins / Q000096:biosynthesis; D006801:Humans; D007109:Immunity; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis; D008875:Middle Aged; D020932:Nerve Growth Factor / Q000097:blood / Q000276:immunology*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000096:biosynthesis* / Q000276:immunology
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D017475:Receptors, Nerve Growth Factor; D020932:Nerve Growth Factor; D020917:Receptor, trkA