Niklas Björkström group

Our group performs translational immunological research studying tissue-resident natural killer cells in the human liver and uterus.

A key focus of the group is to gain insights into the basic biology of tissue resident NK cells in liver and uterus. Through unique collaborations with clinical units at the Karolinska University Hospital, we receive a high number of tissue samples. With respect to the uterus, key questions of interest include detailed characterization of the uterine NK cell KIR receptor repertoires, functional studies of uterine tissue resident NK cells, as well as trying to elucidate the ontogeny of uterine NK cells. In the liver we have a specific focus on human tissue-resident CD49a+ intrahepatic NK cells and study their phenotype, function, development, and role during liver diseases.

Moreover, we have an interest in the role of natural killer (NK) cells in the pathogenesis of liver diseases such as primary sclerosing cholangitis, steatohepatitis (NASH), and hepatitis virus infections (HBV, HCV, HDV). These diseases strongly predispose for tumor development in the human liver and we are also performing tumorimmunological studies evaluating the capacity of NK cells to recognize hepatocellular carcinoma and cholagiocarcinoma. Outside the liver, we also have an interest in NK-cell function during hemorrhagic fever virus infections.

Our studies include phenotypic and functional assessments of NK cells with a focus on differentiation, education, and functional and transcriptional regulation. We work with high-dimensional 22-parameter flow cytometry, CyTOF, microscopy techniques, and new tools for visualization and analysis of highly complex flow cytometry data including SPADE, SNE, and Citrus.

We function in close collaboration with other groups at Karolinska Institutet, including groups at the Center for Infectious Medicine. We participate in Karolinska Institutet - Hannover Medical School exchange program, in the International PSC Study Group.


Niklas Björkström

Group Leader, MD PhD, Associate Professor

Niklas received his M.D. and Ph.D. degrees from Karolinska Institutet in 2011. He completed postdoctoral training at the National Institutes of Health (Bethesda, Maryland, USA). Niklas established an independent laboratory at CIM, Karolinska Institutet in 2013 and is an associate professor at Karolinska Institutet since 2016. His research focuses on human tissue-resident NK cells with a particular emphasis on uterine and liver NK cells. In his spare time he enjoys fly fishing and playing golf.

Martin Cornillet

PhD, research coordinator

Martin finished his PhD in 2014 that concerned the study of specific autoantibodies in Rheumatoid arthritis (Toulouse, France). He is now focusing on the development of Mass Cytometry to analyse immune cells, and particularly NK-cell phenotype and function in different contexts relating to liver physiology/pathophysiology. He likes cooking, practicing sports (karate, tennis, football) and is interested in art and music discovering.

Lena Berglin

PhD, senior laboratory manager

Lena obtained her PhD from Karolinska Institutet in 2015. During her research studies, her main focus was to try to understand how the immune system contributes to the pathogenesis of primary sclerosing cholangitis (PSC) and bile duct cancer. She is specialized within the field of immunohistochemistry and quantitative image analysis, techniques that she now assists other group members with, as well as collaborators outside the group. In her spare time she likes to be in the countryside, to cook and to read crime novels.

Martin Ivarsson

PhD, Assistant Professor

Martin received his PhD from Karolinska Institutet in 2014. After conducting postdoctoral studies in the group of Ashley Moffett at University of Cambridge, UK, Martin has returned to CIM and is now Assistant Professor. He focuses on studying uterine and decidual NK cells in the healthy woman and in different pregnancy disorders. When not at work, he enjoys playing with his daughter and to eat nice food.

Laura Hertwig

PhD, postdoctoral fellow

Laura received her Masters degree in Biochemistry (Freie Universität, Berlin, Germany) in 2011 and completed her PhD in the field of experimental neuroimmunology at the Humboldt Universität, Berlin, in 2016. In her postdoctoral studies she is conducting comparative characterizations of tissue-resident (TR) NK cells across multiple human tissues. Another goal of her studies is to better understand the implication of TR NK cell subsets from the intra- and extrahepatic bile ducts during primary sclerosing cholangitis (PSC). When not at work, Laura enjoys drawing, Scandinavian literature and documentary photography.

Ann-Charlotte Elkan

PhD, research nurse

Ann-Charlotte received her PhD in rheumatology at Karolinska Institutet 2009. She completed postdoctoral training, at the Institute of Environmental Medicine (IMM), Karolinska Institutet, where she was studying the impact of life style factors in developing rheumatic diseases 2011. She was also the initiator/manager and coordinator for a lifestyle clinic at the Dept. of Rheumatology, Karolinska University Hospital, 2011-2012. Ann-Charlotte is now going to coordinate and manage our research conducted at the Gastro Center, Karolinska University Hospital.

Iva Filipovic

Postdoctoral Fellow

Iva completed her MSc in Immunology at Imperial College London where she studied NK cell development. She then went on to complete a PhD at the University of Cambridge in the field of reproductive immunology, with a particular focus on phenotypic and transcriptomic characterisation of tissue-resident innate lymphocytes in the uterus. She now continues to pursue her research interests in studying the roles of tissue-resident NK cells in the context of uterine and liver microenvironments in homeostasis and pathology. When not at work, Iva enjoys fitness, music and photography.

Andrea Ponzetta

PhD, postdoctoral fellow

In 2014 Andrea completed his PhD in Immunology at Sapienza University of Rome, where he focused on NK cell trafficking and development. He then moved as a postdoctoral fellow to Humanitas Clinical and Research Center in Milan to study the role of neutrophils in carcinogenesis in solid tumors and their interaction with unconventional T cells. At CIM since 2020, he is currently interested in the biology of innate-like lymphocytes and in their impact in human tumors. When not at work, Andrea enjoys travelling, cooking and hiking.


Christopher Maucourant

PhD, postdoctoral fellow

Christopher received his Master Degree in immunology and cancerology in 2016. He completed his PhD in 2019 at Sorbonne University in Paris, France, in the field of the signaling pathways involved in NK cells during different arbovirus infections. During his postdoctoral studies, he will characterize tissue-resident NK cells from multiple human tissues, as well as studying the immune response during liver cirrhosis. When not at work, Christopher enjoys athletics (competition at national and international level), cooking, playing piano and to travel.

Benedikt Strunz

MD, PhD-student

Benedikt graduated 2014 as a MD and additionally accomplished a Bachelor's degree in Biology (University of Tuebingen, Germany). His work so far was on the influence of chemotherapeutic drugs on NK cell reactivity, whereas now he focuses on the role of liver resident NK cells in HCV infected patients as well as phenotyping uterine NK cells. In his spare time he likes sports like cross country skiing and rowing, enjoys music and jazz concerts and loves the cinema.

Natalie Stiglund

MD, PhD-student

Natalie received her M.D. from Karolinska Institutet in 2016 and is currently a PhD-student. She is studying the role of NK-cells in fatty liver disease and development of steatohepatitis and hepatocellular carcinoma. In her spare time, she enjoys playing tennis, reading, and travelling.

Isabella Sönnerborg

MD, PhD student

Isabella received her MD from Karolinska Institutet in 2015 and have been working at the Clinic for Transplantation Surgery at Karolinska Hospital since then. Her PhD project is a collaboration with the Department of Transplantation Surgery at CLINTEC. It focuses on intrahepatic and tissue resident lymphocytes in liver transplant patients, with a special focus on NK cells, and their relation to clinical events such as rejection and graft acceptance. In her spare time Isabella enjoys painting, listening to music and spending time with friends and family.

Jonna Bister


Jonna received her MD from Karolinska Institutet in 2018 and is currently a PhD-student. She is studying uterine NK cell development as well as factors regulating KIR repertoire formation in the uterus. In her spare time Jonna enjoys travelling and go to restaurants.

Previous members

Sanna Nyström, now postdoc at University of Tokyo

Kimia Maleki, master-student, now PhD-student at Karolinska Institutet

Sebastian Lunemann, now postdoc at University Medical Center Hamburg-Eppendorf

Julia Hengst, now Production Manager at Miltenyi Biotech

Erik Bergquist, now MD-student at Karolinska Institutet

Otto Strauss, Now working in Medical Affairs in Rare Diseases at Pfizer in London. 

Christine Zimmer, Now working at Glaxo Smith Kline, Germany, but will soon proceed with postdoctoral studies.

Open positions

We are constantly looking for exceptionally talented post docs with an ambition to explore new and unique aspects of human NK cells, liver immunology, and related questions. Contact Group leader: Niklas Björkström (