The effects of aging on the immune system are manifest at multiple levels that include reduced production of B and T cells in bone marrow and thymus and diminished function of mature lymphocytes in secondary lymphoid tissues. As a result, elderly individuals do not respond to immune challenge as robustly as the young.Click to see full answer. Subsequently, one may also ask, how does age affect the immune system?As we age, our immune systems develop defenses against antigens. Others help coordinate other parts of the immune system. Although the number of T cells does not decrease with aging, T-cell function decreases. This causes parts of the immune system to weaken and increases the risk for becoming ill.Additionally, how does stress affect the immune system? Stress, Illness and the Immune System. When we’re stressed, the immune system’s ability to fight off antigens is reduced. That is why we are more susceptible to infections. The stress hormone corticosteroid can suppress the effectiveness of the immune system (e.g. lowers the number of lymphocytes). In this way, how can seniors improve their immune system? 1. Eat a balanced and healthy diet. In order to keep your immune system strong, or even to build it up, eat foods high in nutrients, like vitamins A, C, D, and E. Seniors should focus on eating whole foods, including animal protein, legumes, nuts and seeds, whole grains, and fresh fruits and vegetables.What can weaken the immune system?Your immune system can be weakened by certain medicines, for example. Your immune system can also be weakened by smoking, alcohol, and poor nutrition. AIDS. HIV, which causes AIDS, is an acquired viral infection that destroys important white blood cells and weakens the immune system.