The immune system remains changed for many years, even after a hepatitis C infection heals, according to a new study by Karolinska Institutet, Sweden, and Hannover Medical School, Germany.
The hepatitis C virus (HCV) poses a major health problem globally and, when the immune system fails to fight the virus, can lead to cirrhosis and cancer of the liver. This results in the immune system becoming exhausted.
However, over recent years, most patients with hepatitis C can now be cured of the virus in just a few weeks thanks to revolutionary new medications.
How infections impact the immune system
This study comprised 40 patients with chronic HCV of whom researchers followed before, during and after treatment with the new medications in a bid to investigate impact on the composition and diversity of the immune system.
In order for the immune system to have the ability to fight infections, diversity is vital. Particularly important are natural killer cells (NK), which is a type of white blood cells.
The researchers used flow cytometry and a new measurement method to derive the composition of the immune system, as well as the appearance of NK cells and their function in the blood.
Analysing the immune system’s complexity
Lead on the study, Niklas Björkström, physician and associate professor at the Department of Medicine, Huddinge, Karolinska Institute, said: “Researchers in the field previously focused on analysing individual components but were unable to draw any comprehensive conclusion.
“The immune system is extraordinarily complex, incorporating a large number of interacting parts. We adapted new methods in order to assess and analyse that complexity in a fresh manner.”
It was found that the overall composition of the body’s defence system was affected by the chronic infection, with significantly reduced diversity among the NK cells. Changes remained long after eradication of the virus.
What are the long-term prospects?
Researchers have not yet determined the long-term implications but are currently exploring whether patients have a harder time fighting future infection.
Benedikt Strunz, physician and doctoral student at the same department, added: “One strength of our study is that we monitored patients for more than two years following elimination of the virus.
“To the best of our knowledge, nobody has ever monitored over such a long term like this before.”