PATHOLOGY

Detailed explanation-1: -Mast cells, which reside in connective tissue matrices and on epithelial surfaces, are effector cells that initiate inflammatory responses.

Detailed explanation-2: -Mast cells release histamine as well as other vasoactive molecules, which cause urticaria (hives). If the antigen activates mast cells in deeper tissue, this can lead to angioedema. If the response is prolonged, atopic dermatitis or eczema may occur.

Detailed explanation-3: -Mechanism of Activation. Mast cells are known for their main mechanism of action: IgE-mediated allergic reactions through the FcRI receptor.

Detailed explanation-4: -Mast cells and basophils are the major source of granule-stored histamine, where it is closely associated with the anionic proteoglycans and chondroitin-4-sulfate. Histamine is released when these cells degranulate in response to various immunologic and nonimmunologic stimuli.