Study Finds That Immune System Could Be Affected By Genetics And Environmental Factors

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A new study finds that human immune systems are influenced more by their environment and behavior rather than by genetics. The researchers discovered that past exposure to pathogens and record of immunizations has a greater influence on a person's health and wellness than genes.   

Human immune system is complex and includes white blood cells as well as messenger proteins to combat microbial invasions. Everybody has a slightly different immune system with a unique mixture of hundreds of these cells and proteins.

The overall makeup of the human immune system differs from one person to another, based on both environmental and genetic factors. Although, the major cause of this variation is not known, scientists know that the human immune system can adapt to the environment.

The researchers conducted an experiment on sets of twins to investigate the relative roles that heredity and environmental factors play in illness. It is trite that identical twins share almost identical set of genes, but just half of the genetic code matches in fraternal twins. This made it easy for the researchers to identify and differentiate the aspects of health that is subject to genetic inheritance and that which is a result of environmental condition.

They studied blood samples from 210 fraternal and identical twins that were between the ages of eight and 82. The researchers then examined the samples to check for 200 factors related to health, including 51 varieties of proteins and 95 forms of immune cells, according to TechTimes.

Lead researcher, Mark Davis of Stanford University and his colleagues discovered that the immune systems of identical twins were too varied to be explained by genetics. They found that environmental condition was the predominant factor over genetic inheritance in three quarters of the experiments. However, younger twins were more similar than older ones which invariably means that their immune systems was influenced over time as the twins grew older and were exposed to different environments.

The study also checked the influence of flu vaccines, as identical twins should almost identical immune responses if genetics were the dominant determinant factor of the immune system. The study authors found that there were substantial differences in how bodies of identical twins responded to the vaccines. The level at which antibodies are created in a body proved to be primarily related to environmental conditions which is attributed to the strains of influenza to which a person was exposed during their lifetime.

Many of the identical twins who participated in the study were pairs where only one of the siblings has Cytomegalovirus (CMV) - a highly contagious, but typically harmless virus associated with chicken pox and infectious mononucleosis. The Researchers found a great difference in the pairs, as one was infected and the other was not, which suggest the role of environment in shaping immune system responses, according Science Magazine. They published their findings as "The Variation in The Human Immune System Is Largely Driven By Non-Heritable Influences," in the journal Cell.