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“Important to know what is causing the symptoms”

Professor Olle Söder recalls a discovery that made a difference.

Name: Olle Söder
Title: Professor of Paediatric Medicine, and Senior Physician and Head of the Department of Women's and Children's Health, Karolinska Institutet.

Olle Söder. Photo: Mattias Ahlm
Olle Söder. Photo: Mattias Ahlm Photo: Mattias Ahlm

“In 1986, I discovered that the breast milk of breastfeeding mothers contains a protein, interleukin-1, or IL-1, which stimulates the immune system and causes inflammation. At the time, only a few cytokines had been discovered, as opposed to today, when we know of over a hundred, of which many are used in pharmaceuticals.

I made the discovery on my own, without the help of any colleagues, and published the results in an article with me as sole author. This was more common back then, but it is rare these days.

My discovery of IL-1 in breast milk was important because it provided an answer as to why women with breastfeeding difficulties develop a fever. In this condition, which is a common problem early on in the breastfeeding process, the milk ducts become clogged and milk proteins start to leak out into the blood circulation, causing a fever. Because of this discovery, we now know why IL-1 is a fever-inducing substance. Being able to explain what causes symptoms is important since the person being affected wants to know and it becomes easier for them to manage the situation. The discovery also helped explain why breastfeeding provides infants with protection against infections.

As a consequence of all of this, I was invited to give talks at national and international science conferences and was called “young and promising”, although today I am only “promising”! I now realize that my discovery contributed to me wanting to work in child health care. As we know, paediatric medicine is comprised of every medical condition, from high-tech neonatology to adolescent medicine.

I am currently planning research about children and young people who want to undergo sex reassignment surgery. It is a rapidly growing group at our hormone clinic at the paediatrics clinic, where we understand very little about the biology.”

As told to: Anna-Maria E. Alsand, first published in Swedish in the magazine Medicinek Vetenskap No, 3/2018.