The immune system is the second most complex biological system after the brain. It consists in millions of cells, of various nature, interacting amongst them to keep the organism safe from external enemies (pathogens), such as viruses and bacteria. To better understand how the immune system works, and how it reacts to certain diseases and cures, simulations have been proposed over the years. Amongst them, we may find agent-based ones where the organism’s actors, like cells, antibodies, viruses, and so on, are represented as agents. In this paper, we present the initial design and development of an agent-based simulation of the immune system using a well-known agent framework, JADE. We present the engineering choices we made and the instantiation of some steps of the secondary immune system response. We discuss the implementation in JADE, and we present some experimental results.