Transductional mechanisms of chemoattractant receptors on leukocytes.

摘要: Phagocytic leukocytes contain receptors for chemoattractants on their cell surface. Binding of chemotactic factors to these initiates a number coordinated cellular responses in strict dose-dependent manner. Motility-related functions such as shape change, cytoskeletal rearrangement, and chemotaxis are stimulated by relatively low doses chemoattractants, while microbiocidal or cytotoxic (i.e., secretion lysosomal enzymes stimulation the respiratory burst), require approximately 10- 50-fold higher concentrations agents. The receptor oligopeptide has provided an important model study stimulus-response coupling phagocytic cells. This human polymorphonuclear exists two affinity states that partially interconvertible. Guanine nucleotides regulate convertibility between portion high- low-affinity states, thereby suggesting nucleotide regulatory protein allosterically modifies participates its transduction mechanisms. A fraction high-affinity PMN membranes is not subject guanine regulation appears be formed prior exposure specific agonists. form chemoattractant rapidly internalized at 37 degrees C, formation may dependent aggregation covalent modification receptor. PMNs can divergently manipulated pharmacological agents indicating mechanisms types processes independently regulated. Aliphatic alcohols induce mild fluidization increase average enhance but markedly depress enzyme burst. In contrast, polyene antibiotics bind membrane cholesterol lower receptor's granule enzymes. addition, transmethylation reactions mediated S-adenosyl-methionine appear affinity. When blocked pharmacologically, macrophages reverts ineffective transducing well microbicidal functions.(ABSTRACT TRUNCATED AT 400 WORDS)