Research Highlight of the Year: Sex differences in the immune system

Investigating how sex differences play a role in the immune system 

Researchers uncover how oestrogen and sex chromosomes shape immune responses in arthritis. 

In a study led by University College London, researchers have investigated how sex hormones and chromosomes influence the immune system. They focused on a type of B cell that helps maintain long-term immune responses and may also cause inflammation.

They found that teenage and adult women (before menopause) have more of these B cells than men of the same age. The increase in these cells is only seen after puberty and before menopause, showing a link to the sex hormone oestrogen.

In menopausal women taking oestrogen-based hormone replacement therapies (HRT), levels of this cell were increased to levels seen in younger women. However, this increase with oestrogen treatment was not seen in transgender women, who have different sex chromosomes.

This indicates that both sex hormones and sex chromosomes work together to affect how the immune system behaves, which could influence why women are more likely to develop most types of arthritis than men.  

This research was led by Professor Coziana Ciurtin and co-senior author Dr Lizzy Rosser, and carried out by first author Dr Hannah Peckham and collaborators. It was funded by Arthritis UK.