Maado (protein ah ) taas oo laga soo kiciyo jirka gudahiisa si ay ula dagaalanto caabuq-sidaayasha ilamaqabatada(bacteria) ah.
Waa unugyo yaryar oo ka tirsan dhiigga, gaar ahaan borotiinno ay soo saarto nidaamka difaaca, si ay ula dagaallamaan walxaha qalaad Difaac-kiciye (antigens).