Your Immune System: Natural Born Killer - Crash Course Biology #32

From a channel Lumen includes in full: CrashCourse is Complexly's library of scripted, fact-checked intro courses (philosophy, history, economics, the sciences and more), each a numbered series written with subject-matter consultants and taught by an expert or experienced host.

A 15-minute video from CrashCourse's catalogue; the title names its topic.

Video by CrashCourse, played through YouTube's embedded player.