Advanced Oncology Certified Nurse Practitioner (AOCNP) Certification Practice Test

Which of the following is NOT part of the three lines of defense against infection?

1. Granulocytes

2. Cell-mediated immunity

3. Histamine release

4. Humoral immunity

The correct answer is: Histamine release

The answer is identified as histamine release not being part of the three lines of defense against infection. The three lines of defense against infection typically include: 1. The first line of defense, which consists of physical and chemical barriers, such as the skin and mucous membranes that prevent pathogen entry. 2. The second line of defense is innate immunity, involving various immune cells, including granulocytes (such as neutrophils and eosinophils) that respond quickly to infections and assist in eliminating pathogens through processes like phagocytosis. 3. The third line of defense is adaptive immunity, which encompasses both cell-mediated and humoral immunity. Cell-mediated immunity involves T cells that target infected or cancerous cells, while humoral immunity involves B cells and the production of antibodies that neutralize pathogens and mark them for destruction. Histamine release is part of the inflammatory response and plays a role in the immune response by increasing blood flow and attracting immune cells to sites of infection, but it does not constitute a standalone line of defense. Instead, it acts as a signaling molecule or mediator in the immune response rather than a defensive mechanism itself. Therefore, it does not fit within the framework of the three primary lines of defense against infection.