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Inhibition of neutrophil chemotaxis by purinoceptor agonists
J G Elferink1, B M de Koster, G J Boonen
1Departments of Medical Biochemistry, Biology, University of Leiden, The Netherlands.
Abstract:
Adenine nucleotides inhibited fMet-Leu-Phe-activated chemotaxis by rabbit neutrophils in the micromolar concentration range. The sequence of inhibitory effectiveness was ATP[S] greater than ATP greater than ADP greater than AMP greater than adenosine. In the presence of EDTA, inhibition of chemotaxis by ATP occurred to the same degree as in the presence of Ca2+ (and Mg2+), indicating that neither ectonucleotidases nor Ca2+ fluxes across the plasma membrane are of importance for the inhibitory effect. The inhibitory effect of ATP persisted when the nucleotide was removed after preincubation, before the cells were submitted to chemotaxis. Exposure of neutrophils to ApCpp results in desensitization towards inhibition by ATP. Other nucleoside triphosphates, such as XTP, GTP, ITP, CTP and UTP, also inhibited neutrophil migration. The relative potency of the nucleotides, which are used to discriminate between the subtypes of the P2 purinoceptor, was (at a concentration of 50 microM) ATP greater than ApCpp greater than AppNp greater than MeSATP greater than AppCp. The results suggest that inhibition of neutrophil chemotaxis by purinoceptor agonists is mediated by P2 purinoceptors and that the subtype is different from the P2x or P2y purinoceptor.
Insights
Adenine nucleotides, including adenosine triphosphate (ATP), inhibit neutrophil chemotaxis. This effect is mediated by P2 purinoceptors, suggesting a novel subtype involved in immune cell migration regulation.
Area of Science:
- Immunology
- Cell Biology
- Pharmacology
Background:
- Neutrophil chemotaxis is crucial for immune responses.
- Purinergic signaling, involving nucleotide receptors, plays a role in cellular communication.
Purpose of the Study:
- To investigate the inhibitory effects of adenine nucleotides on rabbit neutrophil chemotaxis.
- To identify the purinoceptor subtype involved in this inhibition.
Main Methods:
- fMet-Leu-Phe-activated chemotaxis assay using rabbit neutrophils.
- Testing various adenine nucleotides (ATP, ADP, AMP, adenosine) and other nucleoside triphosphates.
- Assessing inhibition in the presence of EDTA and Ca2+/Mg2+.
- Investigating desensitization using ApCpp and evaluating relative nucleotide potency.
Main Results:
- Adenine nucleotides inhibited neutrophil chemotaxis in a concentration-dependent manner.
- The order of inhibitory potency was ATP[S] > ATP > ADP > AMP > adenosine.
- Inhibition was independent of ectonucleotidases and Ca2+ fluxes.
- Other nucleoside triphosphates also inhibited migration, with specific potency rankings observed.
- Results suggest involvement of P2 purinoceptors, potentially a novel subtype.
Conclusions:
- Purinoceptor agonists inhibit neutrophil chemotaxis via P2 purinoceptors.
- The data indicate a purinoceptor subtype distinct from known P2X and P2Y receptors.