Mechanisms of Lysosomal Enzyme Release from Human Leukocytes II. EFFECTS OF cAMP AND cGMP, AUTONOMIC AGONISTS, AND AGENTS WHICH AFFECT MICROTUBULE FUNCTION

Abstract

A B S T R A C T Selective release of inflammatory ma-terials from leukocyte lysosomes is reduced by compounds which increase cyclic 3',5'-adenosine monophosphate (cAMP) levels in suspensions of human leukocytes and is augmented by agents which increase cyclic 3',5'-guanosine monophosphate (cGMP) levels in these cell suspensions. Lysosomal enzymes are released in the absence of phagocytosis when cytochalasin B (5 ,ug/ml) converts polymorphonuclear leukocytes (PMN) to secretory cells: lysosomes merge directly with the plasma membrane upon encounter of PMN with zymosan, and cells selectively extrude substantial proportions of lysosomal, but not cytoplasmic enzymes. P-Adrenergic stimulation of human leukocytes produced a dose-related reduction in P-glucuronidase release (blocked by 10' M propranolol) whereas a-adrenergic stimulation (phenylephrine plus propranolol) was ineffective. In contrast, the cholinergic agonist carbamylcholine chloride enhanced enzyme secretion, an effect blocked by 1 0' M atropine. Incubation of cells with exogenous cAMP or with agents that increase endogenous cAMP levels (prostaglandin E1, histamine, isoproterenol, and cholera enterotoxin) reduced extrusion of lysosomal enzymes; in contrast, exogenous cGMP and carbamylcholine chloride (which increases endogenous cGMP levels), increased fi-glucuronidase release. Whereas colchicine (5 X 10-' M), a drug which impairs microtubule integrity, reduced selective enzyme release, deuterium oxide,

Modulation of human neutrophil function by C‐reactive protein

“…In fact, agents that stimulate cAMP elevation inhibit degranulation [19] and PMA-dependant activation of neutrophil oxidative metabolism [30]. Since the CRP levels which evoke substantial elevation in intracellular cAMP are higher than those found to inhibit neutrophil function, the above question remains open.…”

“…Neutrophils, more than 95% pure, were prepared from blood obtained from healthy adult donors (Blood Bank, Trieste, Italy) by dextran sedimentation with 4.5% (w/v) Dextran T500 (Pharmacia, Uppsala, Sweden) in 0.9% NaCl (v/v) (ratio blood:dextran, 5: 1) for 30 min at room tempera- ture and centrifugation on Ficoll Hypaque (Pharmacia, Uppsala, Sweden) following standard techniques [19].…”

Alteration of the cellular fatty acid profile and the production of eicosanoids in human monocytes by gamma‐linolenic acid

“…Leukocytes were harvested from heparinized venous blood (20), diluted 1 : 1 with calcium-and magnesium-poor sterile phosphate buffered saline, and fractionated with Ficoll-Hypaque to separate mononuclear from polymorphonuclear cells. PBM were obtained by adherence to gelatin-coated flasks (21).…”

Decreased H2 Histamine Response of Granulocytes of Asthmatic Patients

“…Modulation of the release of these enzymes follows changes in the concentration of intracellular cyclic nucleotides (19,20 (22), and chopped lung preparations after antigen challenge (23). We reported that histamine inhibition of serumactivated zymosan-induced lysosomal enzyme release from granulocytes is an H2 receptor response and parallels increases in intracellular cyclic AMP (24).…”