An Australian-first twin study is set to investigate why people with highly similar genetic backgrounds can respond very differently to infections, immune-mediated diseases and medical treatments. Researchers from the Snow Centre for Immune Health and the University of Melbourne’s Twins Research Australia will recruit 100 pairs of identical and non-identical twins between the ages of 18 and 80, creating a rare opportunity to separate the effects of inherited biology from those of lifestyle, age and environment.
The central question is how much of a person’s immune behaviour is encoded in DNA and how much is acquired over time. Although identical twins share nearly all of their genetic sequence, their immune systems can diverge substantially as they encounter different infections, medications, diets, stressors and environmental exposures. Non-identical twins, who share roughly half of their genetic variants on average, will provide an additional comparison group for estimating the contribution of heredity to immune variation.
The investigators will use the Snow Centre’s Cyton2 Cell Timer model to study immune cells dynamically rather than relying only on conventional measurements taken at a single point in time. Standard immune tests often provide a snapshot, such as the number of cells present or the concentration of a signalling molecule. The Cell Timer approach is designed to track cellular activity over time, helping researchers observe when immune cells activate, how long they remain active and when their responses decline.
This temporal information could reveal biological differences that are invisible in a static laboratory result. Two individuals may produce similar numbers of immune cells, for example, while differing in how rapidly those cells respond, how strongly they signal to neighbouring cells or how long inflammation persists. By recording these changing patterns, researchers hope to identify immune-response signatures associated with age, sex and genetic inheritance, as well as signatures shaped by lived experience.
Twin comparisons are particularly valuable because they allow researchers to examine biological variation under partially controlled genetic conditions. If identical twins show similar immune responses despite different life histories, the pattern may indicate a stronger genetic influence. Conversely, marked differences between genetically identical twins may point to environmental exposures, previous infections, medication histories or other factors that have altered immune function. The study will not treat genes and environment as separate forces, however; it will also examine how they interact to shape immune responses.
Dr Lucas Calais-Ferreira, Director of Twins Research Australia, said the project would use these contrasts to estimate how much immune variation is genetic and how much is environmental. Twins Research Australia, based at the University of Melbourne, maintains one of the world’s largest volunteer twin research registries. Its involvement provides access to participants with detailed personal and family histories, allowing immune measurements to be interpreted alongside information about health, age and exposure.
The study is also being informed by the experiences of identical twins Nicole and Amanda Campbell, who have previously participated in research through the registry. Nicole has Crohn’s disease, while Amanda has multiple sclerosis, and both conditions are currently in remission. Their different health histories illustrate how genetically similar people can experience distinct immune-related outcomes and provide a compelling example of the biological questions the new research is designed to address.
Professor Jason Tye-Din, Director of the Snow Centre for Immune Health, described the technology as a shift from taking a still photograph of the immune system to recording a video. That distinction could be important for understanding why one person responds well to a vaccine while another develops stronger side effects, or why a treatment controls inflammation in one patient but proves less effective in another. The researchers hope that identifying the timing and intensity of immune-cell activity will eventually support more accurate predictions of treatment response.
The long-term goal is to contribute to personalised medicine for conditions including type 1 diabetes, rheumatoid arthritis, multiple sclerosis and other immune-related diseases. Better knowledge of individual immune behaviour could help clinicians select treatments more precisely, reduce avoidable side effects and develop prevention strategies tailored to a person’s biological risk. The project may also improve understanding of how immunity changes across the lifespan, potentially clarifying why responses to infections and vaccines differ between younger and older adults.
Recruitment is now seeking identical and non-identical twins aged 18 to 80. By combining longitudinal immune-cell tracking with the natural experimental framework of twin research, the Snow Centre and Twins Research Australia aim to build a more detailed picture of why human immune systems vary—and how that variation can be used to make future healthcare more predictive, targeted and effective.
Subject of Research: People
Article Title: Australian-First Twin Study Tracks Why Immune Responses Differ Between Genetically Similar People
Web References: https://www.twins.org.au; https://snowimmunehealth.org.au
Image Credits: WEHI
Keywords: Twins, immune health, immunology, immune response, personalised medicine, infections, vaccines, autoimmune disease, genetic inheritance, environmental factors, Snow Centre for Immune Health, Twins Research Australia
