title: Laser modulation of angiogenic factor production by T-lymphocytes.
abstract: OBJECTIVE
  In previous investigations, small variations in the energy densities of low level light therapy (LLLT) were found to produce significant differences in the proliferation of resting T-lymphocytes in vitro. Pulsing these cells with mitogen in addition to laser therapy produced inhibitory effects regardless of the amplitude of the energy density used. In the current study, the effect of LLLT on the production of angiogenic factor(s) by T-lymphocytes was investigated in vitro.
  
  
  METHODS
  Human T-cells isolated from peripheral blood were prepared in suspension either with or without addition of mitogen. Cell suspensions were irradiated with laser by using the following energy densities: 1.2, 3.6, 6.0, and 8.4 J/cm(2). Wavelength, pulsing frequency, and power output were kept constant at 820 nm, 5,000 Hz, and 50 mW, respectively. After either 3 or 5 days of incubation, lymphocyte supernatants were collected and added as conditioned media to cultured endothelial cells (ECs). The effect on the proliferation of these ECs was assessed over a 72-hour period by using a methylene blue assay.
  
  
  RESULTS
  Endothelial cell proliferation increased significantly when incubated with conditioned media collected from resting T-cells exposed to 1.2 and 3.6 J/cm(2). Day 5 conditioned media produced similar patterns of EC proliferation to that of day 3 but at lower magnitude. Pulsing of T-lymphocytes with mitogen in addition to laser irradiation significantly lessened their angiogenic capability. Conditioned media from 3.6 J/cm(2) laser-treated T-cells induced the maximal EC proliferation in all groups studied.
  
  
  CONCLUSIONS
  It would seem that laser therapy stimulates lymphocytes to produce factor(s) that can modulate EC proliferation in vitro; this effect on the lymphocytes is influenced by (1) the amplitude of energy density used for T-cell irradiation, (2) exposing T-cells to both mitogen and laser, and (3) the duration of T-cell incubation in culture.
authors.affiliation: Tissue Repair Unit, Division of Anatomy and Cell Biology, GKT Medical and Dental School, King's College London, Guy's Hospital Campus, London SE1 9RT, United Kingdom.
authors.forename: A D
authors.initials: AD
authors.lastname: Agaiby
authors.forename: L R
authors.initials: LR
authors.lastname: Ghali
authors.forename: R
authors.initials: R
authors.lastname: Wilson
authors.forename: M
authors.initials: M
authors.lastname: Dyson
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000096:biosynthesis / Q000528:radiation effects*; D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000528:radiation effects; D002478:Cells, Cultured; D004396:Coloring Agents; D017077:Culture Media, Conditioned; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D006801:Humans; D007834:Lasers; D008213:Lymphocyte Activation / Q000187:drug effects / Q000528:radiation effects; D008751:Methylene Blue; D008934:Mitogens / Q000494:pharmacology; D010789:Phototherapy; D013223:Statistics as Topic; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D013997:Time Factors
chemical_list: D043925:Angiogenesis Inducing Agents; D004396:Coloring Agents; D017077:Culture Media, Conditioned; D008934:Mitogens; D008751:Methylene Blue