Histamine self control

Allergy-provoking histamine keeps itself under control, according to a study on page 387. Schneider and colleagues show that basophil precursor cells pump released histamine back into themselves. Once inside, the histamine shuts off its own production and that of allergy-promoting T helper (Th) 2 cytokines.

Basophils and mast cells are the primary histamine producers of the immune system. In mature cells, histamine is stored in intracellular granules and is rapidly released when the cells are stimulated. Once released, histamine triggers acute allergy symptoms by binding to its receptors on vascular endothelial cells and bronchial smooth muscle cells. Histamine can also be produced by nongranular cells, including macrophages and dendritic cells, which secrete the molecule immediately after synthesis.

This group previously described a population of low-granule basophil precursor cells in the bone marrow...