How does the immune system work? Why is the immune system weakened?

If the immune system cannot destroy the germs where they enter the body, it tries to prevent them from spreading and keep the infection limited to that area. The immune system maintains these functions throughout life, protecting us against diseases. The immune system functions through the cooperation of many organs such as white blood cells, thymus gland, spleen, lymph nodes and bone marrow. Diseases that may occur in any of these also cause weakness in the immune system. Breastfeeding, childhood illnesses and vaccinations contribute to the development of the immune system. Infectious diseases are more common in childhood. The immune system is weakened by poor nutrition, unfavorable environmental conditions, lack of sleep, extreme fatigue and stress.

Immunodeficiency is a group of various diseases with a common feature of increased susceptibility to infection.Primary immunodeficiency is classified according to the site of the immune defect: B cells (antibody-making cells), T cells (cells that fight viruses and other microbes and/or help antibody-making cells), phagocytosis (the process by which microbes are taken in and broken down by defense cells) and complement (fluid proteins with various roles in the immune system). Each system can act independently or in concert with one or more of the immune systems. Immune deficiency can be congenital (lack of antibodies due to the X gene), acquired (variable antibody deficiency, acquired immunodeficiency syndrome=AIDS), secondary to a congenital abnormality (DiGeorge syndrome) or idiopathic (cause unknown). Secondary immunodeficiency can result from non-immune diseases (premature birth, malnutrition, Hodgkin’s disease), injury (burns, removal of the spleen) or treatment (steroids, radiation, anticancer drugs). Immune deficiency can be permanent or resolved by treatment of the primary disease.