by Merry Youle — What do mono­cytes, lym­pho­cytes, and neu­trophils all have in com­mon? Well, yes, they are all leu­co­cytes and part of our im­mune sys­tem, but what else? They all can be prompted to mi­grate to the site of in­fec­tion by a spe­cific class of cy­tokines known as chemo­tac­tic cy­tokines, or chemokines for…