Washington Esthetician State Board Practice Exam

Which type of blood cell is primarily involved in immune response?

1. Red blood cells

2. White blood cells

3. Platelets

4. Plasma cells

The correct answer is: White blood cells

White blood cells are the primary players in the immune response, making them essential for protecting the body against infections and diseases. These cells have various types, such as lymphocytes (including T-cells and B-cells), neutrophils, monocytes, and eosinophils, each with specific roles in identifying and attacking pathogens, including bacteria and viruses. In contrast, red blood cells primarily carry oxygen from the lungs to the body's tissues and return carbon dioxide to the lungs, playing no direct role in immune defense. Platelets are mainly involved in blood clotting, helping to stop bleeding rather than fighting infections. Plasma cells, which are a type of white blood cell derived from B-cells, specifically produce antibodies, but they are one component of the broader category of white blood cells; thus, they do not represent the entire immune response system as effectively as white blood cells in general.