Researchers at the Karolinska Institute have shown that white blood cell composition is unique in individuals, and that the composition of the cells may predict immune system response to various forms of stimulation.1 The study paves the way for more individualized treatment of diseases involving the immune system, such as autoimmune disorders, allergies, and various forms of cancer.

The human immune system comprises a complex network of different white blood cells, which coordinate their efforts in order to combat different external and internal threats. This network varies widely among different individuals, but the differences have previously been difficult to measure and understand.

Together with colleagues at the Massachusetts Institute of Technology (MIT) and Stanford University, researchers at the Karolinska Institute’s Science for Life Laboratory (SciLifeLab) have developed a tool for measuring the unique composition of white blood cells in individuals. Researchers have found that the test may also predict how individuals will respond to a given treatment, such as an individual’s response to an influenza vaccine.

“By measuring all populations of white blood cells in the blood at the same time, we can describe the composition of an individual’s immune system and show that this is unique for the individual,” says Petter Brodin, MD, PhD, a physician and researcher at the Karolinska Institute’s SciLifeLab and department of medicine, Solna. “We call this measure the individual’s ‘immunotype.’ We have also found that this immunotype makes the complex immune system more understandable and predictable.”

A human immunotype is not constant, but varies over time in response to external factors. In previous studies, Brodin and his research colleagues have shown that differences in immune defense among individual humans can be attributed primarily to the many different environmental factors unique to each individual, including diet, infections, microflora, and vaccinations.

For the study, researchers analyzed blood samples from approximately 1,500 healthy individuals and tested in vitro how their white blood cells responded to various stimuli. They also vaccinated individuals against influenza and studied which antibody protections the individuals developed thereafter. It transpired that all different types of stimulation could be predicted based on the individual’s immunotype, which was surprising, according to Brodin.

“Our technique can be scaled up, and my hope is that eventually it will be used clinically to predict those individuals who may benefit from a particular immunological treatment or a certain vaccine,” Brodin says. “The technique may also contribute to more individualized drugs to treat autoimmune disease and allergies, as well as immunotherapy to treat cancer, which can be adapted based on the individual’s immune response.”

The study was funded by the European Research Council, Harvard, the Karolinska Institute, MIT, the National Institutes of Health, the National Science Foundation, the Ragon Institute of Massachusetts General Hospital, the Swedish Cancer Society, the Swedish Research Council, and the Swedish Society for Medical Research.


  1. Kaczorowski K, Shekhar K, Nkulikiyimfura D, et al. Continuous immunotypes describe human immune variation and predict various responses. PNAS. 2017;114(30):E6097–E6106; doi: 10.1073/pnas.1705065114.