Introduction au système lymphatique et immunitaire

Immunity refers to the body's ability to resist infections and diseases. All cells and tissues that provide immunity collectively form the immune system.

Immune responses can be innate — nonspecific defenses present at birth or adaptive — specific responses acquired over time. 

The lymphatic system is a vital component, facilitating the adaptive immune response and some elements of innate immunity.

It comprises four main components: lymph, lymphoid cells, lymphatic vessels, and lymphatic tissues and organs.

Lymph is a clear fluid that transports lymphoid cells and plasma proteins.

Lymphoid cells are a group of immune cells that include lymphocytes, macrophages, and dendritic cells.

Lymphocytes are white blood cells that facilitate the adaptive immune response. Dendritic cells are antigen-presenting cells that activate the lymphocytes. Macrophages are phagocytes primarily involved in the innate immune response.

The lymphatic vessels form a network of vessels that transports lymph throughout the body.

The lymphoid tissues and organs, such as the spleen and thymus, provide the sites for the activation of lymphocytes.