Selection Memes

People think T cell development is this orderly classroom education, but it's actually a brutal selection process where 95% of candidates get massacred! The thymus is basically a cellular Hunger Games where immature T cells must prove they can recognize "self" from "non-self" without going overboard. Those that react too strongly to self-antigens? Eliminated. Those that don't react enough? Also eliminated. Only the perfectly calibrated cells graduate from this immunological bloodbath. Nature's quality control is savage - no participation trophies in this immune system!