T CELLS recognize invaders (like viruses) and make more copies of themselves to kill off the invaders. Pessimists’ T cells don’t multiply as quickly as optimists’, allowing invaders to get the upper hand.
NK CELLS circulate in the blood and kill whatever they come across that they identify as foreign (like cancer cells). Pessimists’ NK cells can identify foreign entities, but they don’t destroy them as well as the optimists’ NK cells.
Read more: Optimism Is Healthy and Optimism Interview