What is present in the blood to protect the body from infectons and disease?

The blood contains several components that protect the body from infections and diseases, primarily white blood cells (leukocytes), antibodies, and complement proteins. White blood cells, such as lymphocytes and phagocytes, identify and destroy pathogens. Antibodies are specific proteins produced by B cells that recognize and neutralize foreign invaders. Additionally, complement proteins enhance the ability of antibodies and phagocytes to clear pathogens from the body.