Leukotrienes are secreted by all except –
**Core Concept**
Leukotrienes are a group of eicosanoid inflammatory mediators derived from arachidonic acid through the lipoxygenase pathway. They play a crucial role in the pathogenesis of various inflammatory diseases, including asthma and allergic reactions.
**Why the Correct Answer is Right**
Leukotrienes are primarily secreted by mast cells, basophils, and eosinophils, which are key cells involved in allergic responses and inflammation. These cells release leukotrienes, such as LTC4, LTD4, and LTE4, which cause bronchoconstriction, increased mucus production, and recruitment of inflammatory cells to the site of inflammation. The correct answer is a cell type that does not primarily secrete leukotrienes.
**Why Each Wrong Option is Incorrect**
**Option A:** Mast cells are a primary source of leukotrienes, especially LTC4, LTD4, and LTE4, which contribute to allergic inflammation. Therefore, mast cells are not the correct answer.
**Option B:** Basophils also release leukotrienes, such as LTC4, LTD4, and LTE4, which contribute to allergic inflammation and recruitment of inflammatory cells. Basophils are not the correct answer.
**Option C:** Eosinophils are another cell type that secretes leukotrienes, such as LTC4, LTD4, and LTE4, which contribute to allergic inflammation and recruitment of inflammatory cells. Eosinophils are not the correct answer.
**Clinical Pearl / High-Yield Fact**
Leukotriene modifiers, such as montelukast, are used to treat asthma and allergic rhinitis by inhibiting the action of leukotrienes on their receptors, thereby reducing inflammation and bronchoconstriction.
**Correct Answer:** D