Like other autoimmune diseases, lupus is the result of an immune system that is at war with one’s own body. When someone has an autoimmune disease, theirnatural defense systems can’t distinguish between normal, healthy cells in their bodiesand those that are foreign and infectious. Treating these conditions, then, is a game that plays out in the dark — preventing the immune system from falsely identifying the body’s own cells as a threat is a medical challenge.

That is until now: recently, scientists used a “groundbreaking” therapy to reverse symptoms in five people living with lupus. Published in Nature Medicineon Thursday, the study could prove “revolutionary.“

Globally, lupus affects almost five million people. Lupus has proven to be a bit of a puzzle in medicine. There’s no clear template of what its symptoms look like, how it’s triggered, or how to diagnose it with certainty. People experience everything from fever and fatigue to lesions and swelling. Moreover, the case burden of lupus — and other autoimmune diseases — is disproportionately higher among women (women represent 80% of all cases of autoimmune disease in the U.S.) And nearly 4% of the world’s population live with one or the other of the80 different autoimmune diseases known to science, each intricately changing the quality of life for the individual.

The present study outlines how genetically altered cells helped to send lupus into remission.“We are very excited about these results,” said Georg Schett, a rheumatologist who led the work at Friedrich-Alexander University in Erlangen-Nuremberg. What makes this research interesting too is that four of the five people for whom the lupus cells went into remission were women.

The treatment works by using the patient’s T-cells, the central determinants of the immune system. These are important white blood cells that determine how well the body responds to threats, and act as “weapons” against unruly viruses and diseases. This trait has allowed scientists to come up with a Chimeric antigen receptor (CAR) T-cell therapy that is most commonly used against cancer; the T-cells are collected and modified such that they attack new targets upon being infused back into the body.

This therapy, which was first used in a leukemia patient back in 2015, and has helped in treating some other forms of aggressive cancer, has stood resilient in the case of lupus now. Germany-based doctors used CAR T-cell therapy among severely ill lupus patients aged between 18 and 24, who weren’t responding to other forms of medications and had organ complications.

The immune system’s defense unfolds something like this: when fighting off invaders, two kinds of white blood cells become active: T-cells, and similar-looking B cells that make antibodies. “[T-cell] can act as ‘killer cells,’ attacking cells which have been infected with a virus or another kind of pathogen, or they can act as ‘helper cells’ by supporting B cells to produce antibodies,” explained immunologist Rosemary Boyton, who was not part of the study. In people living with lupus, the antibodies B cells produce were attacking healthy tissues instead of protecting against pathogens.

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In the current research, T-cells upon re-infusion attacked the aberrant B cells among the patients, effectively “rebooting the immune system,” the researchers noted.

Naturally, there’s always a risk of relapse. It is also unclear if the therapy will work for all patients or how long the benefits might last. To say that these people were “cured” of lupus is to overstate the intent of scientific research.

But the present study offers both a hope and promise. Hope, for it uses the proven efficacy of an already existing therapy that scientists have used to combat cancer. Promise, because it presents a treatment that could potentially be used for other autoimmuneillnesses such as rheumatoid arthritis and multiple sclerosis.

“Several other autoimmune diseases which are dependent on B cells and show autoantibodies may respond to this treatment,” Schett explained. “These include rheumatoid arthritis, myositis, and systemic sclerosis. But also diseases like multiple sclerosis may be very responsive to CAR T-cell treatment.”

Such drastic recalibrations of the immune system naturally raise concerns about leaving people at a greater risk of infection. But blood tests showed that the participants’ immune systems recovered four months after the treatment, and were no longer producing the very antibodies that caused lupus. Moreover, they resumedfunctioning in the way they should be by still addressing other foreign pathogens. The researchers tested this by observing the patients’ reaction to different vaccines like hepatitis B and tetanus, and found that the body’s immune response to these infections was what it should have been.

The doctors reiterate that the durability of the CAR T-cell therapy treatment, and its homogenous use among patients, are some factors that need to be closely observed.

But arguably, it’s “a landmark study in the treatment of autoimmunity,” said Aimee Payne, a dermatologist and immunologist at the University of Pennsylvania, who wasn’t involved in the study

The problem with “mysterious” illnesses like lupus is they get sidelined in both medical research and public healthcare. More research on one level could spotlight the experiences of people living with autoimmune diseases and legitimize their struggles. But also, it could spark major improvements for treating women’s autoimmune diseases in particular.