C5a and formyl peptide receptor regulation on human monocytes
| Autor: | D E Van Epps, S J Simpson, D E Chenoweth |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Receptor recycling
Neutrophils Immunology chemical and pharmacologic phenomena Complement C5a Biology In Vitro Techniques C5a receptor Ammonium Chloride Monocytes Cell surface receptor medicine Extracellular Immunology and Allergy Humans Monensin Receptors Immunologic Receptor Receptor Anaphylatoxin C5a Formyl peptide receptor Monocyte hemic and immune systems Chemotaxis Cell Biology Receptors Formyl Peptide Endocytosis Cell biology Receptors Complement N-Formylmethionine Leucyl-Phenylalanine medicine.anatomical_structure Biochemistry Calcium |
| Zdroj: | Journal of leukocyte biology. 51(4) |
| ISSN: | 0741-5400 |
| Popis: | Regulation of C5a and formyl-methionine-leucine-phenylalanine-lysine (fMLPL) receptors on human monocytes has been studied using fluorescein-conjugated derivatives and flow cytometry. Monocytes have receptors for each of these ligands, as evidenced by their ability to bind specifically biologically active fluorescein derivatives of these ligands. Quenching experiments showed that bound fluoresceinated C5a and fMLPL are rapidly internalized at 37°C. Once internalized, monocytes are able to reexpress these receptors, returning to control levels within approximately 90 min. This contrasts with rate differences seen in polymorphonuclear neutrophils (PMNs), where fMLPL receptors return more rapidly (~ 30 min) than do C5a receptors (~ 100 min). Monensin inhibited the reexpression of C5a but not fMLPL receptors, suggesting that a receptor recycling process is necessary to replenish C5a receptors on the monocyte surface. Similar although less efficient inhibition of C5a receptor reexpression was observed with NH4Cl treatment. Reexpression of both G5a and fMLPL receptors was independent of extracellular Ca2+. Treatment with various agents known to stimulate monocytes and PMNs increased the expression of fMLPL receptors in both cell types but either had no effect on or reduced the level of C5a receptor expression. This would indicate that monocytes, like PMNs, have intracellular pools of preformed fMLPL receptors, available for reexpression. These studies show that, like PMNs, monocytes modulate C5a and fMLPL receptors through different mechanisms. Furthermore, monocytes are capable of reexpressing these receptors following exposure to ligand, a theoretical requirement for chemotaxis. |
| Databáze: | OpenAIRE |
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