What if a pathogen crossed your second line defense?

If a pathogen crosses the second line of defense, which includes innate immune responses like inflammation and phagocytosis, the body activates the adaptive immune system. This involves the activation of lymphocytes, such as T cells and B cells, which specifically target and eliminate the pathogen. The adaptive response also generates memory cells, providing long-lasting immunity against future infections by the same pathogen. If the adaptive immune response fails, the infection can progress and potentially lead to illness.