Fluoresceinated chemotactic peptide and high-affinity antifluorescein antibody as a probe of the temporal characteristics of neutrophil stimulation.
Antifluorescein antibody molecules were used to interrupt the stimulation of neutrophils by a fluoresceinated chemotactic peptide. From the results we construct a semiquantitative relationship among ligand-receptor interaction, the time course of cell triggering and response, and aspects of cellular adaptation. The interaction of the antibody with the free fluoresceinated peptide is complete within a few seconds and the peptide-antibody complex neither stimulates the cells nor inhibits subsequent stimulation by unlabeled peptide. When antibody is added to a cell suspension that has been stimulated with the fluoresceinated peptide, we observe that: (i) the apparent membrane depolarization response monitored by a fluorescent dye can be inhibited only if antibody is added within 30 sec of stimulation; (ii) the superoxide response can be inhibited even if antibody is added more than 1 min after stimulation and decays with an intrinsic half-life of about 12 sec; (iii) responses to a second dose of nonfluoresceinated peptide are enhanced if the antibody is added within 2 min of stimulation by the fluoresceinated peptide. These results suggest that different neutrophil responses depend in individual ways on the time course and extent of ligand binding to its receptor. A comparison of these data with the time course of binding permits an estimate of the number of receptors involved in these responses.
D000936:Antigen-Antibody Complex; D002630:Chemotactic Factors / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte; D005452:Fluoresceins; D006801:Humans; D007158:Immunologic Techniques; D008024:Ligands; D009504:Neutrophils / Q000502:physiology*; D009842:Oligopeptides / Q000378:metabolism*; D013997:Time Factors
D000936:Antigen-Antibody Complex; D002630:Chemotactic Factors; D005452:Fluoresceins; D008024:Ligands; D009842:Oligopeptides; C021642:F-chemotactic peptide