Anatomy and Physiology II Practice Test

Which of the following is NOT a primary cell type involved in the immune response?

1. Neutrophil

2. Erythrocyte

3. Monocyte

4. T-Lymphocyte

The correct answer is: Erythrocyte

Erythrocytes, or red blood cells, are primarily responsible for transporting oxygen throughout the body and do not play a direct role in the immune response. They lack the capabilities to recognize pathogens, produce antibodies, or engage in other immune-related functions performed by immune cells. In contrast, neutrophils, monocytes, and T-lymphocytes are all integral components of the immune system. Neutrophils are a type of white blood cell that respond quickly to infection and are key players in the body's first line of defense. Monocytes have the ability to differentiate into macrophages and dendritic cells, which are critical for phagocytosing pathogens and presenting antigens to T-lymphocytes. T-lymphocytes, on the other hand, are essential for cell-mediated immunity, helping to orchestrate the immune response and directly kill infected cells. Thus, erythrocytes are distinctly separated from immune functions, making them the correct answer to the question.