Here's an interesting article about T cell immunity.
>>>There is a catch, however. In many patients who are hospitalised with more serious Covid-19, the T cell response hasn’t quite gone to plan.
“Vast numbers of T cells are being affected,” says Hayday. “And what is happening to them is a bit like a wedding party or a stag night gone wrong – I mean massive amounts of activity and proliferation, but the cells are also just disappearing from the blood.”
One theory is that these T cells are just being redirected to where they’re needed most, such as the lungs. But his team suspects that a lot of them are dying instead.
“Autopsies of Covid-19 patients are beginning to reveal what we call necrosis, which is a sort of rotting,” he says. This is particularly evident in the areas of the spleen and lymph glands where T cells normally live.
Disconcertingly, spleen necrosis is a hallmark of T cell disease, in which the immune cells themselves are attacked. “If you look in post-mortems of Aids patients, you see these same problems,” says Hayday. “But HIV is a virus that directly infects T cells, it knocks on the door and it gets in.” In contrast, there is currently no evidence that the Covid-19 virus is able to do this.
“There are potentially many explanations for this, but to my knowledge, nobody has one yet,” says Hayday. “We have no idea what is happening. There’s every evidence that the T cells can protect you, probably for many years. But when people get ill, the rug seems to be being pulled from under them in their attempts to set up that protective defence mechanism.”<<<
While the latest research suggests that antibodies against Covid-19 could be lost in just three months, a new hope has appeared on the horizon: the enigmatic T cell.
www.bbc.com