Microchimerism as Metaphor

One love. One heart. Let’s get together and we’ll feel all right – the crowd on the Mall in Washington, DC sings Bob Marley today as we celebrate our president elect and his message of unity. He speaks of America coming together with one voice, despite our different races, ideologies, economic blessings, and religions. Obama paints the picture of our country as a stronger whole, greater than the sum of its’ parts; strengthened by the difference within. Somehow, in this very moving moment, my mind thinks of microchimerism as metaphor.
Our symbiotic relationship with microorganisms is generally advantageous, evolving as it did over the past millennia. There is new information about the gut flora “tending”, even nurturing our immune system through its proximity to immunocompetent cells in the intestine. We have normal flora – bacteria present on our skin and in our mouths, all performing vital tasks unbeknownst to us. Even some of our organelles – specialized areas of a cell that perform necessary cellular functions – come from bacterial origin, as does some of our DNA. It is thought that mitochondria – the engine of energy production inside a cell – were once free-living entities that teamed up with other parts of a cell to make our current version a composite whole. Mitochondria are maternally derived – passed along from mother to offspring. Is this the cellular origin of Jewish guilt? If so – it likely passes on other endearing qualities as well!
So our selves are really a mosaic of other microbes and particles that work in concert, and together we seem to feel all right…most of the time.
Yet sometimes it doesn’t work out so well.
Researchers have been studying microchimerism for many years to unravel the mysteries of autoimmunity and the physiology of parturition. Microchimerism defines the presence of cells from another human being that reside (usually happily and un-noticed) within a different human being. Cells from our mothers are admixed in with our blood, and cells from our children are similarly retained in the mother’s system. Some of us have cells from a twin that died in utero that we never knew. This admixing of cells has been studied as a possible mechanism for development of some autoimmune disorders, most recently rheumatoid arthritis. But most of the time this mixing of cells from different beings occurs happily and stays under the radar of the researcher’s microscope.
This invasion, this admixture, this mosaic makes us one – in the composite sense.
We can be redefined as a host for myriad life forms, and cellular remnants of other humans we have known intimately. White mothers with black babies can have black people’s cells within them, genetically speaking. And the same goes for Serbs and Croatians, who have intermarried, and Hutus and Tutsis, and Sunni and Shi’a. This puts the ideologies that divide us in a different light. Is the right hand fighting the left hand? We have so much biology in common with each other. And our interdependence and interrelationships with other organisms suggests that, indeed: we ARE one! A biological marvel of a living, breathing laughing interrelated being.
A microchimerism miracle.


About imh4msla

Dr Schlesinger is an adult and pediatric rheumatologist in Missoula. She was an IMH board member for a few years before assuming the director position in January 2007 when Dr Herbert Swick retired. As IMH director, she promotes collaborative models of care within the hospital, and explores new approaches to teaching the collaborative model to health careers students at the University of Montana. Dr Schlesinger is the track director for the WWAMI program, helping medical students from the University of Washington School of Medicine learn clinical medicine in Missoula.
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