The immune system's resident memory T cells patrol the eye's cornea protecting against infection
In the eye, immunity means a delicate balance between fighting pathogens and avoiding any excess inflammation, that could impede vision. This is especially critical in the outermost layer, the transparent cornea, which must remain clear but is also the front line for infections. Unlike most tissues, the central cornea was thought to be devoid of resident memory T cells, immune cells that recognise previously-encountered pathogens and can quickly respond to infection. Yet new research has overturned that view: sophisticated microscopy techniques revealed that, in mice, infecting the cornea (pictured) with herpes simplex virus (in cyan) leads to recruitment of T cells (in green), which then give rise to more persistent memory T cells. Evidence of similar-looking cells moving around in the corneas of healthy human volunteers suggests our eyes may also have some form of immune memory, with implications for the treatment of chronic dry eye and other eye diseases.
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