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Context: In nonallergic (naive) mice, type I cysteinyl-leukotriene receptors (CysLT1R) mediate the stimulatory effects of cytokines (eotaxin/CCL11, interleukin[IL] − 13), and nonsteroidal anti-inflammatory drugs (NSAID; indomethacin, aspirin) on eosinophil production by IL-5-stimulated bone-marrow. In ovalbumin (OVA)-sensitized mice, airway challenge-induced bone-marrow eosinophilia and eosinopoiesis are prevented by pretreatment with blockers of adrenal glucocorticoid signaling (RU486, metyrapone) or cysteinyl-leukotriene (CysLT) signaling (montelukast). Objective: To define whether allergen challenge modifies subsequent bone-marrow responses to CysLT, NSAID, and cytokines which act through type 1 CysLT receptor (CysLT1R). Methods: We examined the effects of sensitization/challenge, and of in vivo blockade of endogenous glucocorticoid or CysLT signaling, on ex vivo responses to CysLT1R-dependent stimuli. Results and discussion: Challenge abolished the stimulatory ex vivo responses to CysLT1R-dependent agents in the eosinophil lineage. In cultured bone-marrow of naive, sensitized and sensitized/challenged mice, responses to leukotriene D4 (LTD4) in eosinophil differentiation ex vivo shifted from stimulatory (without challenge) to suppressive (following challenge). Both stimulatory and suppressive LTD4 effects were blocked by montelukast. The suppressive LTD4 effect was accounted for by accelerated maturation followed by apoptosis of eosinophils. RU486/metyrapone or montelukast pretreatments before challenge prevented the challenge-induced change in subsequent responses to all these agents. Hence, allergen challenge has two separate effects on bone-marrow: (a) it enhances eosinopoiesis in vivo and upregulates ex vivo responses to IL-5; (b) it promotes a faster, but self-limiting, response to LTD4 and CysLT1R-dependent stimuli. Conclusion: Allergen challenge modifies eosinopoiesis through systemic (glucocorticoid- and CysLT1R-dependent) mechanisms, increasing responses to IL-5 but restricting responses to subsequent CysLT1R stimulation. [ABSTRACT FROM AUTHOR]

Authors demonstrated the presence of allergic manifestations in splenectomized patients following traumatic rupture of this organ. In particular, allergic diathesis, as supported by serum IgE increase, was exclusively found in patients with preserved T helper (h)-2 lymphocyte function. Th-2 function was monitored by measuring serum levels of interleukin (IL)-4, a cytokine involved in IgE synthesis. On the opposite, in splenectomized individuals with a reduced Th-2 function as supported by lower IL-4 serum levels, no IgE increase and allergic manifestations were detectable. On these grounds, authors hypothesize that allergic manifestations may be correlated to splenectomy since its exeresis may favor the persistence of antigens in the blood. Consequentially, in patients with a preserved Th-2 function, antigenic overload may lead to IgE increase and allergy onset. [ABSTRACT FROM AUTHOR]