#bcells

The Central Nervous System is protected from physical trauma and invading pathogens by the surrounding meninges. Meninges contain a variety of innate and adaptive immune cells, such as the T cells, dendritic cells, mast cells, and meningeal macrophages as a defence against pathogens. However, not many studies have focused on B cells. Increased levels of IgG and IgA antibodies have been observed in various diseases states of the CNS. Previously believed to be a result of systemic production and transport through the blood to the brain, newer evidence establishes the existence of localized populations of IgA producing plasma cells in the meninges.

IgA in the gut maintains barrier integrity by preventing their entry through the epithelium and trapping them in the mucus layer. The slow blood flow and low shear forces in the dural venous sinuses make it susceptible to invasion by bloodborne pathogens. Thus the localisation of IgA producing plasma cells in the dural sinuses is a protective measure against the invading pathogens.

Further research suggests that these plasma cells train in the intestines and then migrate to the meninges. What is even more interesting is that the population of IgA producing cells is dependent on the microbiome present in the gut. A depletion in the gut microbiome resulted in a significant reduction in the meningeal B cells. It was also observed that different microbiomes of varying bacterial diversity resulted in a variation of the meningeal plasma cell population. A breach in the intestinal barrier resulted in an increase in meningeal IgA producing plasma cells.

Thus maintaining a healthy gut flora aids the body in more than just digestion.

Link: https://sites.google.com/view/bobthebiotechquer/immunology/cells-of-the-immune-system-pt-2

The CD4/CD8 T cell ratio is a good indicator of the proper functioning of the immune system. T cells are a category of cells that are part of the lymphoid lineage. To learn more about the various cells of the lymphoid lineage, read our new infodump! Click on the link above

Reference:

Mer–/– and Nba2 mice with B cell–specific T-bet deletion exhibit reduced titers of autoantibodies, and reduced frequency of CD11c+ and GC B cells

Researchers at National Jewish Health have identified a trigger for autoimmune diseases such as lupus, Crohn's disease and multiple sclerosis. The findings, published in the April 2017 issue of Journal of Clinical Investigation, help explain why women suffer autoimmune disease more frequently than men, and suggest a therapeutic target to prevent autoimmune disease in humans.

B cells are important players in autoimmune disease. The National Jewish Health research team, led by Chair of Biomedical Science Philippa Marrack, PhD, previously identified a subset of B cells that accumulate in autoimmune patients, autoimmune and elderly female mice. They named the cells Age-associated B cells, or ABCs. Subsequent research showed that the transcription factor T-bet plays a crucial role in the appearance of ABC The findings are important as they are the first evidence that ABCs are drivers of autoimmune disease rather than merely a link to autoimmune disease. ABCs have drawn significant interest since being discovered six years ago. The National Jewish Health research team has expanded its analysis of ABCs outside of autoimmune disease. They are currently studying ABCs involvement in chronic beryllium disease, hypersensitivity pneumonitis and sarcoidosis