Fat tissue clusters act as hubs for local immune responses

Fat tissues, such as the layers surrounding the gut, kidneys and heart, contain clusters of white blood cells called fat-associated lymphoid clusters, or FALCs for short. These structures play an important role in the immune system by acting as meeting points for immune cells to exchange information. Immune cells meet up at various sites in the body, such as the lymph nodes, but these new immune hubs in the body’s fat tissue were only discovered a few years ago. Researchers are now trying to understand their role in the immune system and how they are created.
 
The left hand image shows that in the absence of inflammation FALCs mainly contain T and B cells (stained in green). Upon inflammation, stimulated by using a chemical labelled red in the right-hand image, immune cells called macrophages (stained in blue) ingest the irritant and rapidly travel to the FALC. The macrophages arrive at the cluster within three hours and present the irritant to the resident T and B cells to initiate a local immune response.
 
The formation of FALCs is the subject of a new paper published by researchers at the Babraham Institute, MRC Laboratory of Molecular Biology and the University of Birmingham along with European collaborators in the latest issue of Nature Immunology. The paper examines the distribution of FALCS in different fat tissues in the mouse to understand the cellular and molecular processes which control their development. This research is important for understanding more about how immune responses are orchestrated at sites other than lymph nodes.
 
For more information about the immune system, see our Immune Army: Weapons of Microscopic destruction web page for immune cell descriptions and our immune army video.
 

Image credit:

Dr Yunhua Loo, Veldhoen group
 

Animal research statement:

As a publicly funded research institute, the Babraham Institute is committed to engagement and transparency in all aspects of its research. The research presented here involved the use of mice to analyse changes in the cell population within the FALC after local injection with a chemical to stimulate inflammation. Additionally mice were used in the research associated with the Nature Immunology paper to chart FALC formation and investigate factors required for the recruitment of immune cells to FALCs.
 
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