Researchers discover unexpected dual role of immune system protein

Posted by er134 at Jul 16, 2014 10:57 AM |
Leicester researchers – including three PhD graduates – have released new evidence on the protein properdin

Too much or too little of a certain component of the immune system can affect the chances of getting infectious diseases, according to University of Leicester research.

Researchers from our Department of Infection, Immunity and Inflammation – including three PhD graduates – have published findings about an unexpected dual role of an important component of the immune system.

The paper presents significant new findings about the protein properdin – an important part of the immune system. The new findings show that in some situations a lack of properdin can actually have major benefits – while in others it can be a big disadvantage.

Using mouse models, the researchers investigated the differences in immune responses between individuals deficient in properdin and those with normal amounts of the protein.

When individuals were infected with Streptococcus pneumoniae - bacteria which can cause sepsis and pneumonia in humans – those deficient in properdin had higher survival rates than those with normal levels.

But when individuals were infected with Listeria monocytogenes – which cause an infection called listeriosis in humans – those deficient in properdin had lower levels of survival.

Cellular analysis by the researchers suggests that properdin-deficiency is likely to cause the body to use more of a type of white blood cell known as M2 macrophages – involved in tissue repair – rather than M1 macrophages, whose main role is to kill pathogens

This allowed the researchers to conclude that properdin controls the strength of the body’s immune response by affecting the role of macrophages during infection and inflammation.

The PhD graduates who contributed to the research, alongside principal investigator and corresponding author, Dr Cordula Stover, Senior Lecturer in Immunology (pictured), were Aline Dupont, Nur’Ain Salehen, and Fatima Mohamed (graduation years 2009, 2011, 2014).