Final answer:
White blood cells, also called leukocytes, are involved in the immune response and defend the body against pathogens. They lack hemoglobin and have nuclei.
Step-by-step explanation:
White blood cells, also known as leukocytes, are primarily involved in the immune response to identify and target pathogens in the body. They make up approximately one percent of the cells in the blood and have nuclei. Unlike red blood cells, white blood cells lack hemoglobin. They defend the body against invading microorganisms, clean up debris, and protect against abnormal cells.