Which type of blood cell is primarily involved in the immune response and does not have a nucleus?

The correct choice is the type of blood cell that plays a critical role in the immune response and is characterized by the absence of a nucleus. Red blood cells, specifically, are the main type referred to, as they are designed to carry oxygen from the lungs to the body’s tissues and return carbon dioxide for exhalation. Their lack of a nucleus is significant because it allows for more space to carry hemoglobin, the protein responsible for oxygen transport.

Understanding red blood cells in this context emphasizes their function rather than an involvement in the immune response, which is a key distinction. While white blood cells are indeed crucial for immune defense, they notably contain nuclei and perform various roles, including responding to infections and diseases. Platelets, on the other hand, are cell fragments essential for blood clotting and also lack nuclei. Plasma cells, derived from B-lymphocytes, play a significant role in producing antibodies but, like white blood cells, have nuclei.

In summary, the unique structure of red blood cells, including their lack of a nucleus, is fundamental to their function, distinguishing them from other blood components that are more directly involved in immune response activities.