How does the body fight against a pathogen for the first time?

When the body encounters a pathogen for the first time, the innate immune system responds immediately through physical barriers like skin and mucous membranes, and through immune cells such as macrophages and neutrophils that engulf and destroy invaders. Simultaneously, the adaptive immune system begins to activate, involving T cells that recognize and attack infected cells, and B cells that produce specific antibodies to neutralize the pathogen. This initial response may take several days to develop, during which the body learns to recognize the pathogen for future encounters. Once the pathogen is eliminated, memory cells are formed to provide a faster and more effective response if the same pathogen is encountered again.