Oh no! Francis was bit by a dog off of its leash. The skin is broken, therefore the first line of defence in his immune system is compromised.
Millions of bacteria quickly enter the wound. They start using up resources in Francis' body and double in number every 20 minutes. When a certain population is reached, they begin to change the environment around them!
The first to attack the bacteria are macrophages. In phagocytosis, they swallow, trap, and break down up to 100 bacteria each. They send messenger proteins to call for backup.
Neutrophils leave the blood to help fight the infection. They generate barriers that trap and kill bacteria. They also kill healthy cells during their fight and die after 5 days to prevent further damage.
The dendritic cell (the brain of the immune system) kicks in. It gathers samples of bacteria and presents them on its surface. It also decides whether to call for antibacterial or antiviral forces.
The dendritic cell travels to the closest lymph node where billions of helper or killer T-cells are ready. Once the dendritic cell finds one with a specific set-up, the helper T-cell divides thousands of times.