The allergic reaction to the wasp sting is caused by the immune system's overreaction to the venom. When a person is stung for the first time, their immune system recognizes the venom as foreign and produces antibodies called immunoglobulin E (IgE) to attack it. These IgE antibodies bind to mast cells and basophils, which are white blood cells that release histamine and other chemicals in response to allergens. On subsequent stings, the IgE antibodies recognize the venom and trigger the release of histamine, which causes the symptoms of an allergic reaction, such as swelling, hives, and difficulty breathing. Anaphylaxis occurs when the allergic reaction is severe and affects the whole body, leading to a drop in blood pressure, shock, and in severe cases, death.
Anaphylaxis impacts the body by causing widespread inflammation, leading to dilation of blood vessels, increased permeability of blood vessels, and fluid loss from blood vessels into the tissues, resulting in low blood pressure and shock. Epinephrine helps counteract this by constricting blood vessels, increasing heart rate, and opening the airways, which improves breathing and helps restore blood pressure to normal levels.
A blood smear is a sample of blood that is spread thinly on a glass slide and stained with a dye to allow for examination under a microscope. The leukocyte present in the image is an eosinophil. Eosinophils are a type of white blood cell that are involved in the immune response to parasitic infections and allergic reactions. They contain granules that release enzymes and toxins to help destroy parasites and regulate the immune response. The presence of eosinophils in the blood smear suggests that the patient may have had an allergic reaction to the wasp venom, as eosinophils are often increased in allergic reactions.