The adaptive immune system is switched on by the evolutionarily older innate immune system. This older system is non-specific, whereas the adaptive system is tailored to specific targets.
ð ɪ WORD_BOUNDARY ʌ d æ p t ɪ v WORD_BOUNDARY ɪ m j uː n WORD_BOUNDARY s ɪ s t ə m WORD_BOUNDARY ɪ z WORD_BOUNDARY s w ɪ t̠ʃ t WORD_BOUNDARY ɔ n WORD_BOUNDARY b aɪ WORD_BOUNDARY ð ɪ WORD_BOUNDARY ɛ v ə l uː ʃ ə n ɛ ɹ ɪ l i WORD_BOUNDARY oʊ l d ə ɹ ɹ WORD_BOUNDARY ɪ n n eɪ t WORD_BOUNDARY ɪ m j uː n WORD_BOUNDARY s ɪ s t ə m WORD_BOUNDARY ð ɪ s WORD_BOUNDARY oʊ l d ə ɹ WORD_BOUNDARY s ɪ s t ə m WORD_BOUNDARY ɪ z WORD_BOUNDARY n ɑ n s p ə s ɪ f ɪ k WORD_BOUNDARY w ɛ ɹ æ z WORD_BOUNDARY ð ɪ WORD_BOUNDARY ʌ d æ p t ɪ v WORD_BOUNDARY s ɪ s t ə m WORD_BOUNDARY ɪ z WORD_BOUNDARY t eɪ l ə ɹ d WORD_BOUNDARY t ə WORD_BOUNDARY s p ə s ɪ f ɪ k WORD_BOUNDARY t ɑ ɹ ɡ ɪ t s WORD_BOUNDARY