thapsigargin and Hypersensitivity

During allergic disease, leucocytes infiltrate the affected tissues and release their mediators and cytokines. In this way, the local inflammatory process is induced and maintained. Basophilic granulocytes have been demonstrated in lung and sputum of allergic asthmatics, in nasal mucosa and secretion of allergic rhinitis patients, and in skin lesions of atopic dermatitis patients. The number of basophils correlates with the severity of the disease. Analysis of mediator profiles and cellular contents of lavages of nose, skin and lung during allergic late-phase reactions (LPR) have demonstrated histamine, but not tryptase or prostaglandin D2. The histamine-containing cells have been characterized as basophilic granulocytes. This indicates that infiltrating basophils but not mast cells are activated and release their inflammatory contents in the LPR. We are interested in the cellular mechanisms that determine the degranulation of basophils during LPR. Basophil activators, such as allergens and activated complement, are not present at these sites. However, cytokines that prime basophils but do not induce degranulation, such as interleukin-5 (IL-5) and granulocyte/macrophage colony-stimulating factor (GM-CSF), have been detected at sites of LPR. We have now observed that after emptying intracellular Ca2+ stores by means of the Ca2+ adenosine triphosphatase (ATPase) inhibitor, thapsigargin, basophils become extremely sensitive to stimuli that do not affect the Ca2+ stores themselves but that induce degranulation, such as the phorbolester, phorbol myristate acetate (PMA). The most interesting finding was that although both thapsigargin and IL-3, IL-5 or GM-CSF do not induce basophil degranulation by themselves, a 2 min preincubation of basophils with thapsigargin followed by addition of one of these cytokines resulted in extensive histamine release: IL-3 induced 71 +/- 7% histamine release (conc1/2max 6 pM), IL-5 induced 43 +/- 8% histamine release (conc1/2max 41 pM) and GM-CSF induced 57 +/- 10% histamine release (conc1/2max 140 pM). Interestingly, the effect of thapsigargin could be mimicked by platelet-activating factor (PAF) (range 10(-9) to 10(-6) M), although to a lesser extent. Our results indicate that basophil degranulation in tissues during late-phase reactions might be caused by a combination of mediators or cytokines depleting Ca2+ stores, as platelet-activating factor or thapsigargin do, concurrent with activation by interleukin-3, interleukin-5 or

Topics: Asthma; Basophils; Bronchoalveolar Lavage Fluid; Calcium; Cell Degranulation; Chymases; Complement C5a; Cytokines; Granulocyte-Macrophage Colony-Stimulating Factor; Histamine; Histamine Release; Humans; Hypersensitivity; Interleukin-3; Interleukin-5; N-Formylmethionine Leucyl-Phenylalanine; Nasal Lavage Fluid; Phorbol Esters; Platelet Activating Factor; Prostaglandin D2; Receptors, IgE; Serine Endopeptidases; Skin; Tetradecanoylphorbol Acetate; Thapsigargin; Tryptases

From a series of 4'-[(trifluoromethyl)pyrazol-1-yl]carboxanilides derived from 4-methyl-4'-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl]-1,2,3-thiadiazole-5-carboxanilide, one inhibited thapsigargin-induced Ca2+ influx in Jurkat T cells (IC(50)=77 nM) and exhibited high selectivity for the CRAC channel over the VOC channel (index: >130). Another acted as an inhibitor for both T lymphocyte activation-induced diseases and ovalbumin-induced airway eosinophilia in rats (ED(50)=1.3 mg/kg) p.o.

Topics: Anilides; Animals; Calcium; Calcium Channel Blockers; Calcium Channels; Calcium Signaling; Enzyme Inhibitors; Female; Humans; Hypersensitivity; Interleukin-2; Jurkat Cells; Lymphocyte Activation; Male; Mice; Pulmonary Eosinophilia; Pyrazoles; Rats; Rats, Inbred BN; Structure-Activity Relationship; T-Lymphocytes; Thapsigargin