Which type of white blood cell plays a key role in the immune response?

Lymphocytes play a crucial role in the immune response as they are a type of white blood cell that is essential for identifying and responding to pathogens. They are primarily involved in the adaptive immune system, which is responsible for targeting specific antigens. There are two main types of lymphocytes: B cells, which produce antibodies that can neutralize pathogens, and T cells, which can kill infected cells or help regulate the immune response.

In contrast, platelets are involved in blood clotting and do not have a direct role in the immune response. Erythrocytes, or red blood cells, are responsible for carrying oxygen throughout the body and are not involved in immunity. Granulocytes, another type of white blood cell, do contribute to the immune response, particularly in the innate immune system, but they are not as pivotal in the adaptive immune response as lymphocytes. Thus, the key functions of lymphocytes make them central to the body's ability to fight infections and develop immunological memory.