Title: Regulation of cd18 expression in human neutrophils as related to shape changes
Abstract:ABSTRACT The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including ...ABSTRACT The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetylglycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10 7 to 10 5 M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10 4 M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10 5 M cytochalasin D. Cytochalasin D (10 5 M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils. Increased CD18 expression in response to phorbol myristate acetate, but not in response to chemotactic peptide was inhibited by the protein kinase C inhibitor Ro 31-8220 (10 6 to 10 5 M). Ro 31-8220 (10 5 M) alone increased CD18 expression of initially resting cells. Furthermore, the phosphatase inhibitor okadaic acid (5 M) and calyculin A (0.04 μM) suppressed CD18 expression in chemotactic peptide-treated cells, but there was no detectable effect in phorbol myristate acetate-stimulated cells. This indicates that at least two different pathways mediating CD18 expression are operative in human neutrophils, one being protein kinase C-dependent, the other(s) probably being protein kinase C-independent.Read More
Title: $Regulation of cd18 expression in human neutrophils as related to shape changes
Abstract: ABSTRACT The study analyses the distribution and quantitative expression of surface CD18 of neutrophils exposed to distinct stimuli that produce different types of continuous shape changes, including types that are associated with locomotion and others that are not. The chemotactic peptide N-formyl-L-norleucyl-L-leucyl-L-phenylalanine, colchicine and nocodazole were used to induce a polarized locomotor morphology, phorbol myristate acetate, 1,2-dioctanoylglycerol and 1-oleoyl-2-acetylglycerol to induce non-polar motile cells ruffling all over the surface and 2H2O to induce non-polar cells performing circus movements as have been previously described. Except for colchicine and nocodazole, these stimuli increased surface expression of CD18. Thus, stimulated shape changes are frequently, though not always, associated with increased surface expression of CD18. High concentrations (10 7 to 10 5 M) of phorbol myristate acetate but not of chemotactic peptide induced down-regulation of surface CD18. Cytochalasin D (10 4 M) stimulated CD18 expression even though it inhibited shape changes. The surface distribution of CD18 determined by light microscopy was uniform in unstimulated cells or in various forms of stimulation except for cells treated with 10 5 M cytochalasin D. Cytochalasin D (10 5 M) produced CD18 accumulation at the pole opposite the F-actin cap. Experiments with colchicine, nocodazole, 2H2O and cytochalasin D suggest that microtubules as well as microfilaments modulate surface expression of CD18. The results suggest that protein kinase C and phosphatases play a role in regulating surface expression of CD18 in neutrophils. Increased CD18 expression in response to phorbol myristate acetate, but not in response to chemotactic peptide was inhibited by the protein kinase C inhibitor Ro 31-8220 (10 6 to 10 5 M). Ro 31-8220 (10 5 M) alone increased CD18 expression of initially resting cells. Furthermore, the phosphatase inhibitor okadaic acid (5 M) and calyculin A (0.04 μM) suppressed CD18 expression in chemotactic peptide-treated cells, but there was no detectable effect in phorbol myristate acetate-stimulated cells. This indicates that at least two different pathways mediating CD18 expression are operative in human neutrophils, one being protein kinase C-dependent, the other(s) probably being protein kinase C-independent.