Second line of defence.

If a pathogen gets past the first line of defence, then body sends in the first wave of immune sentries in the form of the innate immune system. The innate immune cells are our oldest and simplest defence and like the foot soldiers, they can only do what they are inherently able to do and can’t learn and adapt. ..

The job of the innate immune system is to find the pathogen, take basic defensive steps and call for back up through cell signalling. This is done by secreting chemical messengers that bind to a specific cell and change it (man to man combat). By attaching to the surface of a cell and changing the cells around it (short range artillery). Or by trggering glands elsewhere to release hormones through the circulation (long range artillery)