AsianScientist (Jul 9, 2014) – B cells, thought to specialize only in the production of antibodies, have now been shown to also participate in the development of regulatory T cells. These findings have been published in the Journal of Immunology and ranked among the top ten percent of the articles in the latest issue.
T cells develop in the thymus gland, a soft triangular organ in the chest cavity. From a naïve or undifferentiated state they are gradually ‘educated’ to become helpers, or warriors, or regulators.
Until now, the only non-thymic cells known to educate the regulators were dendritic cells, which travel to the thymus to deliver ‘antigen’, samples of substances toxic to the body. We now know that B cells can do the same thing.
As newfound educators of T cells, B cells become much more interesting and complex characters, potentially useful in helping to prevent organ rejection, or control inflammatory bowel disease, or quell autoimmune conditions.
That is because regulatory T cells control how killer T cells behave and can effectively prevent the warriors from attacking ‘self’ tissue, or tissue perceived as foreign. In the case of organ transplantation, several studies have shown that high levels of regulatory T cells can prevent organ rejection.
“Regulatory T cells are critical in the outcome of an immune response, so anything that in turn regulates them becomes very interesting to immunologists,” said Associate Professor Shane Grey from Sydney’s Garvan Institute of Medical Research.
“Everyone is interested in finding ways to treat autoimmunity and prevent transplant rejection. Expansion of regulatory T cells should help in both cases. Our finding suggests it should be possible to set up systems that harness B cells to expand regulatory cells.”
The Garvan lab members worked with mice genetically modified to express high levels of ‘BAFF’, a substance that increases survival of B cells. The higher number of B cells overall allowed researchers to track the activity of B cells in the thymus.
“It has been known for years that some B cells travel to the thymus, but no-one has understood why,” said Dr. Stacey Walters, Senior Research Assistant at Garvan and first author of the study.
“Our experiments showed clearly that B cells participated in the creation of regulatory T cells—the more B cells that were in the thymus, the higher the number of regulatory cells generated. That direct correlation raises interesting possibilities.”
“One possibility is using BAFF, a non-toxic substance, to ramp up the B cell count of patients before transplant procedures. It will be very interesting to test whether or not that would prevent rejection,” she said.
The article can be found at: Walters et al. (2014) A Role for Intrathymic B Cells in the Generation of Natural Regulatory T Cells.
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Source: Garvan Institute.
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