You can learn about the immune system in the context of aging from this page.
Adaptive Immune System
The adaptive immune system is a marvel that only vertebrates are blessed with. This complex mechanism protects us from a wide variety of threats, including viruses and cancer. T cells and B cells, which constitute the backbone of our adaptive immune system, begin their journey in the bone marrow. B cells mature there, while T cell progenitors migrate to the thymus to eventually become full-grown T cells. The T and B in the cells' names designate thymus and bone marrow, respectively.