American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which cells primarily release histamine into the blood?

1. Monocytes

2. Basophils

3. T-lymphocytes

4. Neutrophils

The correct answer is: Basophils

Basophils are the cells primarily responsible for releasing histamine into the blood. These white blood cells are a type of granulocyte and play a key role in the body's immune response, particularly during allergic reactions and in response to infection. When basophils are activated, they release various substances, including histamine, which is a chemical signal that contributes to vasodilation, increased vascular permeability, and other effects that facilitate the inflammatory response. The significance of histamine release from basophils lies in its role in mediating allergic responses. When allergens are encountered, basophils are often one of the first responders, helping to amplify the immune system's reaction. The release of histamine contributes to symptoms such as itching, swelling, and redness associated with allergic reactions. Other cell types mentioned have different primary functions. For instance, monocytes are involved in phagocytosis and can differentiate into macrophages and dendritic cells but do not primarily release histamine. T-lymphocytes are crucial for cell-mediated immunity and do not play a direct role in histamine release. Neutrophils are primarily involved in the response to bacterial infections and inflammation but also do not release histamine as their main function. Understanding the specific roles of these immune