Which component of blood is primarily involved in immune response?

White blood cells, also known as leukocytes, are the primary component of blood involved in the immune response. They play a crucial role in defending the body against infections and foreign invaders. There are several types of white blood cells, including lymphocytes, monocytes, neutrophils, eosinophils, and basophils, each with specific functions tailored to different aspects of the immune response. For instance, lymphocytes are essential for the adaptive immune response, as they are responsible for recognizing specific pathogens and generating a targeted attack.

In contrast, red blood cells are primarily responsible for transporting oxygen from the lungs to the rest of the body and carbon dioxide back to the lungs for exhalation. Platelets are essential for blood clotting and help prevent bleeding, while plasma proteins play various roles, including maintaining osmotic pressure and transporting substances, but they are not directly involved in the immune response like white blood cells are. Hence, white blood cells are the key players when it comes to the body's defense mechanisms against infections and diseases.