immunology allergic disorders
Overview of Immunodeficiency Disorders
Key Points
Secondary (acquired) immunodeficiencies are much more common than primary (genetic) immunodeficiencies. Primary immunodeficiencies can affect humoral immunity (most commonly), cellular immunity, both humoral and cellular immunity, phagocytic cells, or the complement system. Patients who have primary immunodeficiencies may have nonimmune manifestations that can be recognized more easily than the immunodeficiencies. Immunity tends to decrease with aging partly because of age-related changes; also, conditions that impair immunity (eg, certain disorders, use of certain drugs) are more common among older adults. 