Twin study asks if immune systems are shaped by our genes or our lives

Twin study seeks to determine whether immune systems are primarily shaped by genetic factors or environmental influences. Identical twins Nicole and Amanda Campbell, now in their forties, have vastly different immune responses despite their genetic similarities. Nicole was diagnosed with Crohn's disease at age 11, while Amanda was diagnosed with multiple sclerosis at age 24.

A new Australian-led study aims to understand why genetically similar individuals can have differing immune responses. Immune systems are complex networks that protect the body against infections and diseases. White blood cells recognize and remember how to fight known pathogens, with vaccines mimicking viruses or bacteria to train the body to produce antibodies.

However, immune responses can vary between individuals due to genetics and environmental factors like diet, lifestyle, past infections, and stress. The Snow Centre for Immune Health is studying 100 healthy sets of twins by analyzing blood samples to monitor immune cells' responses under controlled conditions. Researchers hope to gain insights into how immune cells divide, survive, and die, which influences how people respond to vaccines, infections, and diseases.

Twin studies have been used in various fields, including ophthalmology, to distinguish genetic influences from environmental factors. A 2022 study on identical twins, one with multiple sclerosis and one without, found specific differences in immune cell communication that may contribute to the disease's development. Australian researchers are focusing on healthy twins to eliminate disease as a confounding factor, as demonstrated by a 2015 study that found past infection history, particularly with cytomegalovirus, to be the most significant driver of an individual's immune response.