Study note

Lymphocytes and macrophage populations in chronic inflammation

THE CONTEXT

Lymphocytes amplify chronic inflammation, while macrophages differ in their developmental origins and activation-dependent functions.

•

Microbes and environmental antigens activate T and B lymphocytes, which amplify and propagate chronic inflammation.

•

Although lymphocytes principally provide adaptive immunity against infections, they are often present in chronic inflammation.

•

Lymphocyte activation tends to make inflammation persistent and severe.

•

Strong chronic inflammatory reactions, including granulomatous inflammation, depend on interactions between lymphocytes and macrophages.

•

Lymphocytes may be the dominant cell population in autoimmune and other hypersensitivity diseases.

•

During inflammatory reactions, most tissue macrophages are derived from hematopoietic precursors.

•

Some long-lived resident tissue macrophages arise from embryonic precursors that populate tissues early in development.

•

Classically activated M1 macrophages are induced by microbial products and cytokines, particularly IFN-g.

•

M1 macrophages phagocytose and destroy microbes and dead tissue debris and can potentiate inflammatory reactions.

•

Alternatively activated M2 macrophages are induced by other cytokines and contribute to tissue repair and resolution of inflammation.

NEETx

Learn. Practise. Remember.