StemCell Therapy

Read: Immunology is where intuition goes to die

In epic tales of the immune system, B cells and their antibodies tend to hog the limelight. Antibodies, which are proteins that drift through the blood, are easy to capture and measure; theyre sometimes powerful enough to waylay a virus before it has the chance to break into a cell. But no antibodies would be produced without the help of T cells, which coax B cells into maturing and play vital roles in their training regimenloyal wingmen at the ready. T cells are also formidable foes in their own right, capable of recognizing virus-infected cells and forcing them to self-destruct.

T cells dont undergo the same supercharged mutation process that their B-cell colleagues do. They are stuck with the pathogen sensors theyre born with. But the starting repertoire of T cells, and the number of bugs they can recognize, is similarly massive. And like their B-cell counterparts, T cells are capable of remembering past pathogenic encountersand their discerning gaze is especially difficult to elude.

When viruses undergo a substantial costume change, it can disrupt this iterative process. Its a big part of why flu vaccines have to be updated every year, Ellebedy said: We are always trying to catch up with the virus.

But coronaviruses mutate far more slowly than flu viruses do. And this new one has yet to undergo a makeover that fully neuters the vaccines weve developed against it. I think theres probably a very small probability that there will be complete escape, David Masopust, an immunologist at the University of Minnesota, told me.

B cells and T cells develop so many unique ways of recognizing a given virus that any one mutation, or even a handful, wont fully thwart them. A change to the equivalent of a viruss elbow, for example, will have little impact on a T cells ability to recognize its earlobe. Memory cells will rapidly seize upon commonalities between the two versions of the virus; in some people, this alone could be enough to nip an infection in the bud.

Certain memory cellsespecially T cellsmight have enough flexibility to recognize a modified version of their viral target. Experts call this cross-reactivity, and its a crucial part of the T cell way of life, Laura Su, an immunologist at the University of Pennsylvania, told me. Some scientists have hypothesized that T cells previously marshaled against other coronaviruses, such as those that cause common colds, might even play a small role in quelling this new one.

Even in the complete absence of memory and cross-reactivity, the body still has a huge reserve of backup cellsthe multitude of B and T cells that were not triggered by the first go-round with the virus, Su said. The war against variants is not a fight just for veterans: Chances are, rookies are waiting in the lymph nodes to be called to the front lines. Depending on the extent of the viruss metamorphosis, another infection, perhaps another illness, may be possible. But the body is not left wholly defenseless.

See the rest here:
The Body Is Far From Helpless Against Coronavirus Variants - The Atlantic

This entry was posted on February 14, 2021 at 7:25 pm and is filed under Immune System. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed. |