immune cell (B cell T cell)成熟之前有training, 認到自己cell就會死, 所以剩返通常只可以認外來野
另外早期有innate immune response 可以sense 到外來DNA / RNA (physical structure 唔同), 再provoke adaptive immune response (真係認病毒抗原
加快Build up response 一定係vaccine ,因為可以剌激immune memory.
另外就係boost innate immune response, 但係未有人實際咁做