Normally, when an invading virus triggers an immune response, B cells form into self-contained structures in lymph node follicles, where they rapidly multiply, mutate, and swell into an immune army of billions, each carrying a copy of its own. signature. antibody protein on its surface. However, almost as soon as this happens, cells engage in a deadly game of musical chairs at the molecular level, competing to bind to a small number of viral fragments to see which one is best suited to attack it. Losing cells immediately begin to die by the millions. Ultimately, only the B cells with the antibody that forms the strongest bond to the invading virus survive to be released into the bloodstream.
It’s a good thing others don’t, Sanz explains, because up to 30% of the antibodies produced in the race to fight an invading virus will target parts of the body the system is supposed to protect.
When Sanz examined the blood of patients with severe covid, he found that many quickly created antibodies to fight the virus. But most of these antibodies were produced by rapidly multiplying the B cells generated outside the normal process of elimination. Sanz had seen this phenomenon in lupus before, and many believed it was a hallmark of immune dysfunction.
Eline Luning Prak, a professor at the University of Pennsylvania hospital, says she’s not surprised. Luning Prak, an expert in autoimmune diseases, notes that when the body is in crisis, the usual controls can be relaxed. “It’s what I call an all-terrain immune response,” she says. “When you die from an overwhelming viral infection, the immune system says at this point, ‘I don’t care, give me anything.'”
Still a mystery
In March, James Heath, president of the Institute for Systems Biology in Seattle, worked with a long list of eminent immunologists to publish what he believes to be the first scientific paper characterizing the immune systems of patients two to three months later. have been infected. Heath and his colleagues found that the people who survived took one of four different paths. Two groups of patients experienced complete recovery – one group with severe acute covid and a second with the milder form of the disease. And two other groups – some of whom had severe acute covid and some of the initial symptoms of which were mild – continued to experience massive immune activation.