title: Vasoactive intestinal peptide inhibits fMLP-induced respiratory burst in human lymphocytes.
abstract: N-Formyl-Methionyl-Leucyl-Phenylalanine (fMLP) induced in lymphocytes the production of reactive oxygen intermediates in a process which was inhibited by the presence of Vasoactive Intestinal Peptide (VIP) in a dose-dependent response at VIP concentrations in the range 10(-10)-10(-7) M. The dissociation constant for the high-affinity receptors of VIP agrees with the ID50 of the activation of adenylate cyclase which are close to 0.2 nM VIP, whereas the ID50 for the inhibition by VIP of fMLP-induced chemiluminescence approaches to 5 nM VIP. Both IBMX and Forskolin produced in lymphocytes an inhibition of fMLP-induced chemiluminescence. The degree of inhibition was ascertained to be additive in the presence of the above indicated agents and suboptimal concentrations of VIP. The saturation by cAMP of its putative target, the regulatory subunit of protein kinase A, appears to be required for the onset of the inhibitory effect of VIP. This study provides evidence of the molecular signal, namely cAMP, which provokes an inhibitory effect on chemoatractant-stimulated human lymphocytes and further support a role for VIP as a mediator in the neuroimmune system.
authors.affiliation: Departamento de Bioquímica Médica y Biolgía Molecular, Hospital Universitario Virgen Macarena, Facultad de Medicina, Sevilla, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Bellido
authors.forename: M A
authors.initials: MA
authors.lastname: López-González
authors.forename: C
authors.initials: C
authors.lastname: Pedrera
authors.forename: M
authors.initials: M
authors.lastname: Lucas
mesh_terms: D000242:Cyclic AMP / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008163:Luminescent Measurements; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D016897:Respiratory Burst / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
chemical_list: D014660:Vasoactive Intestinal Peptide; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000242:Cyclic AMP