As women age, they produce an increasing number of 鈥渒iller鈥� immune cells, which hunt down and destroy infected cells. This discovery, and the fact that the same isn鈥檛 true of men, could help to explain why women are less likely to catch infections but have higher rates of autoimmune conditions.
We already know that women tend to have stronger immune systems than men, but because studies tend to or male animals, we lack a detailed understanding of how immunity really differs between the sexes.
鈥淎dult females are often excluded from drug trials or clinical studies due to concerns about hormonal fluctuations during the menstrual cycle,鈥� says at Yale University, who wasn鈥檛 involved in the new study.
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To fill this gap, at the Barcelona Supercomputing Center in Spain and her colleagues analysed data on nearly 1.3 million immune cells collected as part of a . The cells came from blood samples collected from more than 500 female and around 400 male participants, making this the largest study of its kind so far. They were aged from 19 to 97 and all were living in Australia. There were no transgender or non-binary people in the study.
The researchers found that the number of a subset of CD8 T-cells, which form part of the immune system by killing other cells, increased with age in the female participants, but the same pattern wasn鈥檛 seen in the male volunteers.
This may be why women have a reduced risk of infections, as these T-cells target infected cells. It could also explain why women are more likely to have an autoimmune condition, if the same T-cells mistakenly attack healthy cells.
For instance, these T-cells also showed genetic changes that have previously been linked , when immune cells attack the gut, and, again, these changes were only seen in the female participants.
This suggests that differing numbers of these T-cells could partly account for sex-based differences in infections and autoimmunity, though the study didn鈥檛 demonstrate a causal link.
Future research could address this question, the researchers wrote in their paper, and look for the same trend in more diverse populations, as the data they used only included people of north European ancestry.
The results could pave the way for sex-tailored vaccines or therapies against autoimmune conditions. 鈥淎ny studies that probe sex and age differences in immune responses are important for better understanding of how we might diagnose or treat certain groups of patients based on their sex and age,鈥� says Iwasaki. But first, these findings have to be replicated in other studies, she says.
bioRxiv
