Each spends the entirety of its life waiting for a very specific trigger, like a hunk of a dangerous virus. Some T cells are microscopic assassins, tailor-made to home in on and destroy infected cells; others coax immune cells called B cells into producing virus-attacking antibodies. The first time a virus infects the body, this response is sluggish; it takes several days for the immune system to sort out which T cells are best suited for the job at hand. Usually, this process operates best when T cells must battle the same pathogen again and again. In theory, cross-reactive T cells can “protect almost like a vaccine,” said Smita Iyer, an immunologist at the University of California, Davis, who is studying immune responses to the new coronavirus in primates.

Source: New York Times August 06, 2020 21:00 UTC