immunology allergic disorders
Overview of Immunodeficiency Disorders
Geriatrics Essentials: Immunodeficiency
Some decrease in immunity occurs with aging. For example, in older adults, the thymus tends to produce fewer naive T cells; thus, fewer T cells are available to respond to new antigens. The total number of T cells does not decrease (because of oligoclonality), but these cells can recognize only a limited number of antigens. Signal transduction (transmission of antigen-binding signal across the cell membrane into the cell) is impaired, making T cells less likely to respond to antigens. Also, helper T cells may be less likely to signal B cells to produce antibodies. The number of neutrophils does not decrease, but these cells become less effective in phagocytosis and microbicidal action. are particularly important to immunity. Risk of Overview of Disorders of Calcium Concentration is increased in older adults, partly because with aging, the intestine becomes less able to absorb calcium. Also, the elderly may not ingest enough calcium in their diet. Certain disorders (eg, Diabetes Mellitus (DM) , 