For most of his career as a researcher, Lars Björck has sought to understand how bacteria manage to evade the human immune system. One of his discoveries is now saving the lives of patients with kidney disease who previously found it very difficult to receive a kidney transplant. He describes research as a combination of perseverance and imagination - and a fair few failures. Meet the winner of the 2026 Fernström Nordic Prize.
For most of his career as a researcher, Lars Björck has sought to understand how bacteria manage to evade the human immune system. One of his discoveries is now saving the lives of patients with kidney disease who previously found it very difficult to receive a kidney transplant. He describes research as a combination of perseverance and imagination - and a fair few failures. Meet the winner of the 2026 Fernström Nordic Prize.
It was 2001, and Lars Björck's doctoral student was initially annoyed that the experiment they had carried out had not worked. Nothing appeared to have happened to the bacteria, Streptococcus pyogenes, which had grown overnight in test tubes containing human blood plasma.
But when Lars Björck took a closer look at the analysis, he noticed something unexpected. One of the proteins in the blood plasma had been cleaved - and not just any protein.
"I remember it as if it were yesterday: I could see straight away that it was the IgG antibody that had been cleaved. But what impressed me most was that none of the other proteins in the blood plasma were affected," says Lars Björck.
Right then and there, he was reminded of a seriously ill patient he had met whilst working as a junior doctor at the nephrology clinic in Lund.
"He eventually received a kidney - but it was only a few days before his body rejected it."
IgG is the most common type of antibody in the blood and an important part of our defence against infections. The streptococcus had developed a molecular defence mechanism, like a pair of scissors, to cut apart antibodies that bind to the bacterium's surface. The antibody was still able to recognise the bacterium, but lost its ability to alert other parts of the immune system. This made it more difficult for the immune system's cells to recognise and kill the bacterium.
Björck realised that the same mechanism might perhaps be used when antibodies interfere with a kidney transplant. What if it were possible to use the bacterial enzyme to remove the antibodies that trigger the rejection of the new kidney - before the patient underwent the transplant?
The discovery marked the start of a long journey. Lars Björck and his research team succeeded in identifying and isolating the streptococcal enzyme that cleaves IgG, which has been named IdeS. In animal studies, they were able to show that mice with a fatal IgG-induced disease could be cured with an IdeS injection.
For the past 14 years, IdeS has been used as a treatment for a group of kidney patients for whom transplantation was previously very difficult. In total, 20 per cent of all those in need of a kidney transplant have IgG antibodies that react to the donor kidneys, which would lead to the rejection of the transplanted kidney.
"With IdeS treatment prior to the transplant, these patients now have a prognosis that is just as good as that of patients who did not have the antibodies to begin with," says Lars Björck.
The fact that an enzyme from one of the most significant disease-causing bacteria in humans can be used to treat a serious illness is a unique and inspiring research finding.
The medicine has been approved for use in Europe since 2020, and a decision from the US Food and Drug Administration (FDA) on whether it will also be approved in the US is expected towards the end of 2026. The enzyme is also being investigated in other conditions where antibodies drive the disease process, including Goodpasture's syndrome - a progressive inflammatory disease affecting the kidneys and lungs - and the neurological condition Guillain-Barré syndrome, which affects the nerves and can lead to muscle weakness and paralysis.
Björck can see further potential applications. In the case of several severe autoimmune conditions, patients are treated by extracting their blood plasma and purifying it to remove IgG antibodies.
"It is a complicated and protracted course of treatment. With IdeS, it would be possible to get rid of the antibodies within half an hour after a single injection. However, for the enzyme to be used to treat new diseases and syndromes, clinical trials are required for each specific application."
A life in research amongst bacteria and antibodies
To understand how bacteria became Lars Björck's teachers, we need to go back to his secondary school days. It was then that he read Charles Darwin and became captivated by the idea of evolution. It became something of a lodestar - and as a young researcher, he and his supervisor, Ingemar Berggård, became interested in how the human immune system had developed over the course of evolution.
"If you want to study evolution, you need a suitable organism that reproduces rapidly, so that you can track many generations over a short period of time. That makes bacteria a good choice."
This interest then led to the question of how the human immune system deals with bacteria and which proteins are involved in this interaction. After the defence of his doctoral thesis, he began working as a junior doctor at the central bacteriological laboratory in Lund.
Eight years later, he had discovered several previously unknown bacterial proteins.
The key bacterial proteins
Proteins are the bacteria's toolkit. Among other things, they help the bacteria to obtain nutrients, attach themselves to our cells and defend themselves against the immune system. By finding out what different bacterial proteins do, it is also possible to understand how bacteria survive in the human body and cause disease.
And that was how he first became interested in the bacterium that produced that strange result in the laboratory in 2001: group A streptococcus, Streptococcus pyogenes. It can cause anything from throat and skin infections to very serious and fatal infections. But it also has a unique characteristic - it only infects humans.
"That was one of the reasons why we focused on it. The fact that it is so focused on infecting humans must mean that it has developed defence mechanisms specifically against our immune system."
You could think of the streptococcus as a burglar that has spent a very long time practising how to get past a single alarm system: the human immune system.
A protein that found its way into laboratories around the world
In addition to the IdeS enzyme, Lars Björck, together with Göran Kronvall, discovered protein G, another streptococcal protein, which was found to bind very strongly to IgG antibodies.
"Once we'd isolated the protein, we saw that it binds very strongly to IgG antibodies. In 1985, the pharmaceutical company Pharmacia took charge of the commercial launch and began producing and selling protein G. It was a hit," says Lars Björck.
Protein G became a sort of all-purpose tool for IgG antibodies. By attaching the protein to small beads or to a column, researchers can isolate and purify IgG antibodies from a complex mixture, and then use the antibodies for medical and biotechnological applications.
It is also an example of how basic research can result in an application that was not apparent from the outset. Lars Björck did not begin studying streptococci in order to develop medicines or laboratory tools, but to understand the interaction between the bacterium and the human immune system.
The question comes first
What advice would you give to young researchers?
"I used to tell my doctoral students that the research you do is only as good as the research question you ask. Actually, that's the hardest part - coming up with a question that's interesting and that perhaps no one else has asked. It can be a mix of realism and fantasy."
The only problem is that experiments rarely go as the researcher intended.
"After all, most of the experiments people come up with end in failure. One quality that is therefore very important is not to give up. As my American colleagues say - you need tenacity. It can be tough to carry on working for long periods when everything's going pear-shaped. But that's something you just have to put up with."
Looking back, it might not even be his own discoveries that he is most proud of. He keeps coming back to the people who were part of the research team.
"Some of my students have gone on to become very talented researchers. Now that I'm in the later part of my life and career, that's probably what makes me happy more than anything else - that I have helped inspire a number of people to develop the same passion for research that I had."
In December, Lars Björck and his wife Kristina will celebrate their 50th wedding anniversary. They have three children and eight grandchildren. He enjoys reading fiction - which he does often - listening to music, gardening, walking the dog. He has a keen interest in sport - at the time of interview, he was getting ready to leave on a cycling holiday. For many years, the people at the lab ran a 10k together every Wednesday, in the scenic surroundings of Skrylle Nature Reserve. Lars Björck held the group's record for a long time.
"Unfortunately, we then recruited an Irish visiting researcher who smashed my record by several minutes. He was a marathon runner."
Lars Björck is now 77 years old. When asked how it feels to have made all these scholarly discoveries, he replies:
"We humans long for moments of clarity and beauty. As a scientist, there are times when you come up with something that solves a problem you've long been interested in. It's the ultimate reward for all that hard work - and it's highly addictive. That's why I still cycle to work with a sense of joy and anticipation that the day will bring something new and exciting."
