Blood–thymus barrier

Blood–Thymus Barrier

The blood–thymus barrier is a biological barrier that separates the blood from the thymus tissue. It is a crucial component of the immune system, playing a vital role in the development and maturation of T cells.

Structure

The blood–thymus barrier is composed of several layers. The outermost layer is the endothelium of the blood vessels, which is lined with a continuous layer of basement membrane. This is followed by a layer of pericytes, and then another layer of basement membrane. The innermost layer is composed of epithelial reticular cells that form the cortex of the thymus.

Function

The primary function of the blood–thymus barrier is to protect the developing T cells from premature exposure to antigens. This is achieved by preventing the direct contact of circulating antigens in the blood with the thymic microenvironment. The barrier also regulates the exchange of substances between the blood and the thymus, allowing only certain molecules to pass through.

Clinical Significance

Disruption of the blood–thymus barrier can lead to several health issues. For instance, it can result in the premature exposure of T cells to antigens, leading to autoimmune diseases. Moreover, the barrier's integrity is crucial in preventing the spread of infections and malignancies to the thymus.

See Also

• Thymus
• Immune system
• T cells
• Autoimmune diseases