Immunology is a very complex, biological subject. It involves many players (different cells, molecules and physical changes). Here are two examples from the Australian organization named Australian and New Zealand Society for Immunology about some basic concepts in immunology (the videos are not embedded here, but clicking on the videos takes you to Vimeo, where they can be seen). The videos can also be found on ASIs homepage.
Below is also an MoA animation about immunotherapy, made for the biotech company MonTa Biosciences.