Mast Cells and Red Bumps
Just under our skin are capillaries carrying blood with its circulating red cells () and a variety of white blood cell types. Just outside of the capillaries, in the tissue of the dermis, lurk specialized immune cells called MAST CELLS.
When we get itchy red bumps on our skin from contact with an "allergen", it is due to how our mast cells respond to the allergen.
Mast cells are covered with molecules of Immunoglobulin E antibody (IgE, ).
There are antigens () in dust mites, in their droppings () and shed exoskeletons. Once these antigens get under the skin of an allergic host, the antigens cause mast cells to go berserk.
Antigens stick to the mast cell IgE antibodies, causing granules () in the mast cell to fire their contents into the surrounding tissue.
This releases a host of inflammatory materials - leukotrienes, tumor necrosis factor, interleukin-4 and other cytokines that turn on other inflammatory cells.
These materials cause fluid to leak from the capillaries and white cells () including neutrophils, T cells and eosinophils to leave the circulation. The end result is a "local inflammatory response", a red, itchy welt.
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