Hataraku Saibou (tv) Episode 3 〈Bonus Inside〉

These are mature T-lymphocytes that have not yet been activated by encountering their specific antigen.

Unlike bacteria, viruses must "hijack" a host cell's machinery to reproduce, which the anime depicts as the cells turning into "zombies".

Feeling useless, the Naive T Cell flees and meets the Dendritic Cell . The Dendritic Cell provides the necessary "motivation" (activation) for the Naive T Cell to mature into an Effector T Cell , allowing him to join the battle with renewed power.

A Macrophage appears, wielding a large weapon to clear out the virus. She identifies the virus as Type B and contacts Helper T Cell for reinforcements.

The White Blood Cell (Neutrophil) arrives to fight, but the sheer number of infected cells makes it difficult to manage alone.

Cells at Work! (TV Series 2018–2021) - Episode list - IMDb