title: Specificity and reversibility of chemotactic deactivation of human monocytes.
abstract: The chemotactic deactivation of human monocytes was studied to provide insight into the mechanism of chemotaxis. Deactivation was dependent on the dose of chemoattractant and time of incubation. A concentration in the cell suspension of 10(-8) M N-formylmethionylleucyl phenylalanine (FMLP) for 45 min at 37 degrees C led to 60% suppression of the subsequent specific chemotactic response. Higher concentrations of FMLP led to almost 100% specific suppression. Deactivation was specific under all conditions used. The response to a nonrelated chemoattractant, human serum-derived C5a, was unaffected by incubation in FMLP. Deactivation was also transient. If cells were deactivated at 37 degrees C with FMLP, they recovered within 6 h at 37 degrees C from this deactivation. Both phenomena, deactivation and recovery from deactivation, were temperature dependent. Monocytes could not be deactivated at 0 degrees C, and they did not recover from deactivation when kept at 0 degrees C. Thus, specific deactivation appears to require cellular metabolism, involving loss of receptors or blocking of a step between receptor occupancy and response.
mesh_terms: D000706:Anaphylatoxins / Q000494:pharmacology; D002630:Chemotactic Factors / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D003182:Complement C5 / Q000494:pharmacology; D015936:Complement C5a; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism; D006801:Humans; D007700:Kinetics; D008715:Methionine / Q000031:analogs & derivatives*; D009000:Monocytes / Q000502:physiology*; D009239:N-Formylmethionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009842:Oligopeptides / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D044042:Receptors, Formyl Peptide; D013696:Temperature
chemical_list: D000706:Anaphylatoxins; D002630:Chemotactic Factors; D003182:Complement C5; D009842:Oligopeptides; D011956:Receptors, Cell Surface; D044042:Receptors, Formyl Peptide; D009239:N-Formylmethionine; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D008715:Methionine