New research has demonstrated a link between the development of long-COVID in patients and an alteration in their immune system.
The team of scientists at the University of Manchester have discovered a persistent alteration in the immune system of patients, six months after they have been hospitalised for COVID-19. They say that this could be associated with poorer health outcomes.
The team – based at the University’s Lydia Becker Institute of Immunology and Inflammation and supported by the UK Coronavirus Immunology Consortium (UK-CIC) – have managed to identify an immunological signature occurring in some of the patients that were associated with unresolved chest x-rays, indicating those patients had a poorer clinical outcome.
The study has been published in the journal Med.
The immune system
The researchers identified immune characteristics in recovering COVID-19 patients are associated with negative impacts on health following a COVID-19 infection.
Looking at the immune cell characteristics of over 80 recovering COVID-19 patients from Manchester hospitals, the researchers found that changes to B cells – a type of lymphocyte – that occur during the peak of COVID-19 hospitalisation were largely restored by six months of recovery. However, changes to T cells, another lymphocyte, persisted.
Study author Dr Joanne Konkel from The University of Manchester said: “Our study details persistent immune alterations in previously hospitalised COVID-19 patients up to 6 months after hospital discharge. Significantly, we outline an immune signature associated with poorer clinical outcomes in convalescent patients.
“Association, however, is not a causation, and what we now want to understand is what other long COVID symptoms this signature could be associated with and whether it could be used to identify the patients that should be most closely followed after hospital discharge.”
High levels of cytotoxic T cells
The signature present in the group of patients with the poorer clinical outcome was characterised by the team as having high levels of cytotoxic T cells – which can destroy other cells – as well as elevated production of special types of proteins called type-1 cytokines.
Study author Dr Madhvi Menon from The University of Manchester said: “It remains to be established if these immune alterations are unique to COVID-19, or whether they are also observed following other severe respiratory infections.
“Follow-up studies will determine whether this signature can provide a tool to identify acute COVID-19 patients at risk of Long COVID, enabling close monitoring and improved clinical management.”
Study author Dr John Grainger from The University of Manchester and deputy Director of the Lydia Becker Institute said: “Given the vast numbers of previously infected individuals across the globe, it is vital to understand the impact of COVID-19 on the phenotype and functional potential of all immune cells.
“This will allow for better understanding of the long-term impacts of being hospitalised with COVID-19 on subsequent anti-pathogen or auto-inflammatory responses.”