Related Experiment Videos
Correlation of the biologic effects and binding of cytochalasins to human polymorphonuclear leukocytes
Abstract:
Treatment of human PMNs with cytochalasins (CE, CD, CB, and H2CB) results in alteration of cell morphology and inhibition of cell motility. Morphological changes are similar to those reported for nonamoeboid fibroblasts--rounding, zeiosis, and arborization. Mean cell velocity of PMNs, as measured by quantitative analysis of time-lapse videotape recordings, was reduced to 0.1 micron/min (control, 7.3 +/- 4.2 micron/min). Phagocytosis by PMNs, as measured by phagocytosis of latex beads, was inhibited by 75%. The relative potency of the cytochalasins for inducing morphological change or for inhibiting locomotion and phagocytosis is similar to their relative potencies for affecting non-amoeboid cells: CE greater than CD greater than CB greater than or equal to H2CB. Quantitative binding of 3H-CB to purified PMNs under equilibrium conditions reveal two types of specific CB binding sites: high-affinity sites (KD approximately 3 x 10(-7) M, 3 x 10(6) sites/cell) and low affinity sites (KD approximately 2 x 10(-6) M). The relative affinities of the cytochalasins for the high-affinity and low-affinity CB binding sites parallel their relative potencies for inducing biologic effects (i.e. CE greater than CD greater than CB greater than or equal to H2CB).
Insights
Cytochalasins alter human neutrophil (PMN) morphology and inhibit motility and phagocytosis. Their potency in affecting PMNs mirrors effects on non-amoeboid cells, linked to specific binding sites.
Area of Science:
- Cell Biology
- Biochemistry
Background:
- Cytochalasins are known to affect cellular processes.
- Human neutrophils (PMNs) are critical immune cells involved in motility and phagocytosis.
Purpose of the Study:
- To investigate the effects of various cytochalasins (CE, CD, CB, H2CB) on human neutrophil morphology, motility, and phagocytosis.
- To determine the relationship between cytochalasin binding affinity and their biological effects on neutrophils.
Main Methods:
- Treatment of human PMNs with different cytochalasins.
- Quantitative analysis of cell morphology and motility using time-lapse videotape recordings.
- Measurement of phagocytosis using latex beads.
- Quantitative binding assays to determine cytochalasin B binding sites on PMNs.
Main Results:
- Cytochalasins induced morphological changes in PMNs, including rounding, zeiosis, and arborization.
- Mean cell velocity of PMNs was significantly reduced (0.1 micron/min vs. 7.3 micron/min control).
- Phagocytosis of latex beads by PMNs was inhibited by 75%.
Conclusions:
- The relative potency of cytochalasins for affecting PMNs mirrors their effects on non-amoeboid cells.
- Two types of specific cytochalasin B binding sites (high and low affinity) were identified on PMNs.
- The affinity for these binding sites correlates with the cytochalasins' potency in inducing biological effects.