How do white blood cells defend against invading pathogens?

They can engulf and ingest pathogens; this is essentially the white blood 'eats' the pathogen. They secrete (release) antitoxins which counteract the toxins released by pathogens. The toxins they release are often what make us feel ill. The last element of their defence is releasing antibodies which 'attack' and bind the pathogen to stop it binding to cells and help to kill the pathogen.