When viruses and bacteria have managed to cross the body's first defense barrier (the inflammatory reaction), a second line is put into action: this is adaptive immunity. This second protective shield is specific to vertebrates. It implements a complex mechanism using particular white blood cells: lymphocytes. Film directed by Thierry Imbert from the Corpus website. With the support of the investment for the future (Estim). Duration: 6 min. 29 sec.