Polymorphonuclear leukocytes from asthmatics release more calcium from intracellular stores and have enhanced calcium increase after stimulation with N-formyl-methionyl-leucyl-phenylalanine.
Polymorphonuclear leukocytes isolated from peripheral blood of asthmatics appear to be primed to release more reactive oxygen species than cells of healthy subjects. The enhanced agonist-induced rise in the intracellular free calcium concentration may be responsible for this increased respiratory burst. To test this hypothesis we studied the N-formyl-methionyl-leucyl-phenylalanine- and cyclopiazonic acid--(an inhibitor of Ca(2+)-ATPase of intracellular calcium stores) induced calcium increase in the polymorphonuclear leukocytes of 28 subjects (16 with moderate asthma, 69.6% +/- 8.3% predicted normal peak expiratory flow and 12 normal controls) using a fluorescent probe Fura-2AM at 100 nM and 1 mM extracellular calcium concentrations. In 1 mN calcium, the N-formyl-methionyl-leucyl-phenylalanine-induced calcium increase was 1.7-fold higher in asthmatics than in healthy subjects. Similarly, the contribution of calcium from intracellular stores to the calcium response to N-formyl-methionyl-leucyl-phenylalanine was higher in asthmatics (55% +/- 14% vs. 39% +/- 14%, P < 0.01). The pool of calcium released from intracellular stores by N-formyl-methinoyl-leucyl-phenylalanine and cyclopiazonic acid was 2.3- and 2.2-fold larger than in control cells. There was a correlation between maximal intracellular calcium concentration related to N-formyl-methionyl-leucyl-phenylalanine-induced calcium release from intracellular stores and forced expiratory volume in 1 s expressed as percentage predicted and reversibility in asthmatics (r = 0.63, r = -0.53, P < 0.05). In conclusion, polymorphonuclear leukocytes of asthmatics exhibit an altered calcium response that is mainly dependent on increased calcium release from intracellular stores.
Nowak
D
D
Department of Pneumology and Allergology, Medical University of Lodz, Poland.
Bialasiewicz
P
P
Piasecka
G
G
Antczak
A
A
Krol
M
M
D000328:Adult; D001249:Asthma / Q000097:blood*; D002118:Calcium / Q000097:blood*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D016022:Case-Control Studies; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*
D004791:Enzyme Inhibitors; D007211:Indoles; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid