IMMUNOLOGY Bios 328 a textbook-based study of immunology

IMMUNOLOGY Bios 328 a textbook-based study of immunology Spring 2003 http://www.lehigh.edu/~sk08/Courses/Bios328/mainpage.htm

The INTEGRATED View A series of visual reminders

A series of visual reminders A series of visual reminders A series of visual reminders

The whole enchilada Organs of the immune system

BONE MARROW: Site of pluripotent stem cells. Those in the lymphoid lineage develop into B-cells and T-cells. T-cells are educated in the thymus; B-cells are educated in the bone marrow.

B-cells receive signals from STROMAL cells which include: fat cells, endothelial cells, fibroblasts, and macrophages . The THYMUS

The distribution system The great escape. Cells circulate and migrate

The principal drainage system Liquids of the circulatory system leak out; become interstitial fluids. The fluid which permeates connective tissue constitutes a

few per cent of the total blood volume. This plasma is not actively pumped; rather it is moved by the constriction of the surrounding musculature; as

such, the liquid becomes a drainage system. Valves prevent back flow. The fluids drain into progressively larger ducts and, ultimately, into the thoracic duct

which returns the fluid to the circulatory system by emptying into the subclavian vein. The lymph node

The lymph node Lymph arrives in afferent vessels and leaves in efferent vessels. Afferent delivers Ag; efferent, Ab. Node is divided into cortex,

paracortex, and medulla. Paracortex is the command center. There T-cells see Ags on stromal cells (interdigitating dendritic cells and macrophages); contact B-cells. B-cells migrate to cortex and into

primary follicles; Ag stimulation continues with Agpresentation on follicular dendritic cells; proliferative response transforms primary follicle into secondary follicle. Mature B-cells differentiate into

plasma cells that migrate to medulla (to be away from Ag stimulating the response) Plasma cells secrete a single type of Ag-specific Ab into efferent fluids.

Another view of a lymph node The spleen The spleen

Red pulp: degradation and consumption of exhausted erythrocytes. White pulp: site of immunological monitoring of blood. Red and white pulp are separated by marginal zone. PALS (periarteriolar lymphoid sheaths) surround blood arteries; arteries deliver blood to sinuses of the marginal zone. Ags are

displayed on dendritic cells. PALS have follicles (like lymph nodes). MALT (mucosal-associated lymphoid tissue) Back to the effector cells