A patient develops sneezing, itching, and nasal congestion within minutes of exposure to pollen. Laboratory analysis indicates that mast cells in the nasal mucosa have rapidly degranulated. Which substances released from mast cell granules are primarily responsible for the immediate vascular and smooth muscle effects in this reaction?

A patient with mismatched blood transfusion develops rapid destruction of transfused red blood cells due to antibodies binding to antigens on the donor cells. Complement activation follows, leading to hemolysis. Which category of hypersensitivity reaction best explains this immune response?

A patient receives a tuberculin skin test during a routine medical evaluation. Two days later, the injection site becomes firm, red, and swollen. The physician explains that this reaction occurs because immune cells recognize the antigen and recruit additional inflammatory cells over time. Which type of hypersensitivity reaction best explains this response?

A patient with a severe peanut allergy accidentally consumes food containing peanuts and rapidly develops airway constriction, widespread hives, and a dangerous drop in blood pressure. Emergency medical personnel administer a drug that quickly relaxes airway smooth muscle and increases blood pressure. Which drug is most appropriate for this situation?