The body can defend itself from pathogens using white blood cells, the respiratory system, and digestive system. White blood cells fight against the pathogens by ingesting them. Certain white blood cells called lymphocytes produce antibodies that destroy pathogens by finding antigens, the foreign chemicals released by the pathogen. The respiratory system defends the body from pathogens each time you sneeze or cough. Cilia and mucus also protect the body by trapping dirt and other particles. The digestive system destroys pathogens with saliva, mucus, enzymes, and stomach acid.