destroying something is a kind of method for getting rid of something & the immune system gets rid of bacteria once they have invaded the body ->  the immune system destroys bacteria once they have invaded the body  the immune system destroys bacteria once they have invaded the body & bacteria is a kind of pathogen sometimes ->  the immune system destroys pathogens that have invaded the body  white blood cells are a part of the immune system & white blood cells are a kind of cell ->  white blood cells are a kind of cell that are part of the immune system  the immune system destroys pathogens that have invaded the body & white blood cells are a kind of cell that are part of the immune system ->  white blood cells are a kind of cell that is a part of the immune system which destroys pathogens that have invaded the body  white blood cells are a kind of cell that is a part of the immune system which destroys pathogens that have invaded the body & a kind of cell helps destroy pathogens -> white blood cell destroys pathogens in the body