|Photo: Aryn Martin|
In explaining the concept of microchimerism, Aryn discusses the exchange of cells between a mother and her foetus, problematises the self/non-self model dominant in immunology, and emphasizes the significance of the use of geopolitical metaphors to explain this phenomenon – and consequently the links between the foetus and the nation-state.
Simon Dawes: Your article is concerned with the biological relationship between a mother and her unborn child, and more specifically with the bidirectional cell trafficking between foetal and maternal bodies. Could you begin by explaining this process, and the concept of 'microchimerism'?
Aryn Martin: While a woman is pregnant, intact living cells sloughed off from the fetal body pass through the placenta and enter womens’ bodies. They are found not just in her bloodstream, but sometimes also in her bone marrow, skin, liver and in many other tissues. While this phenomenon has long been recognized during pregnancy, a more recent and surprising finding is that fetal cells can outlast pregnancy by decades, and even proliferate and differentiate, becoming part of womens’ bodies. This cell movement – called “trafficking” – happens in both directions, so that mothers’ cells can be located in their children as well. This persistence of typically tiny numbers of cells is called “microchimerism”; the same word is sometimes used in organ transplantation. The term is derived, via a roundabout genealogical pathway, from the Chimaera (a hybrid monster from Greek mythology).
SD: How does this challenge the legitimacy of the S/NS (self/non-self) model that is currently dominant within immunology?
AM: The S/NS model was first proposed in the 1949 by MacFarlane Burnet and has more or less held sway in immunology since then. Its premise is that organisms intrinsically recognize and tolerate cells and tissues that are “self” and likewise distinguish and reject that which is not self, or “foreign.” As a testimony to the hold of the S/NS view, the scientists to first describe maternal microchimerism were widely disbelieved and the paper was rejected repeatedly before being published. Pregnancy has always had an uncomfortable relation to the S/NS doctrine: a woman’s unlikely “tolerance” of the genetically dissimilar fetus is cast as a mystery in need of an explanation. In other words, why doesn’t a mother destroy her fetus much like an organ recipient rejects a foreign organ (in the absence of drugs to prevent this)? In the history of immunology, pregnancy has typically been set aside as a transient exception to the rule, not wholly disruptive, particularly when fetus and mother are rendered as genetically distinct and physically separate entities. Microchimerism – increasingly recognized as a ubiquitous event that implicates us all – cannot be so easily bracketed, and it is one in an increasing number of phenomena not well explained by the self/non-self model.
SD: You argue that there has been a change in the use of geopolitical metaphors to explain microchimerism, suggesting a shift in the construction of the 'body at war' (which rejects 'foreign' cells) to a body that is capable of assimilating 'migrant' cells. Can you explain the link between the ideas of the 'nation' and the 'fetus', and between this very specific (medical-biological) context and wider social changes (to cosmopolitanism and the nation-state)?
AM: Language in science, as elsewhere, is a deeply complicated and dynamic beast, where we language-users are at best partially aware of the resonances implied by our word choices. In investigating this research domain from a science studies perspective, I noticed a surprisingly robust package of metaphors used by researchers in their technical writing, interviews, and speech. These “foreign” cells were “trafficking”, “populating”, and “taking up residence.” They were “stowaways” being “harbored” in their new “homes”. My goal in this paper is to reflect on what work this colourful language is doing in this research domain, without over-determining its causal power. I take figurative language to be inevitable and productive in scientific theory and practice (rather than dispensable “bias”). Yet the particular metaphors are not “innocent” and have a bearing on what is seen and known.
In this case, I argue that the lens of “foreign-ness” that microchimerism researchers inherited from immunology predisposed them to assume that microchimeric cells were wreaking havoc in foreign territories. This assumption instigated a flurry of research into the connection between microchimerism and so-called autoimmune disorders, where it was supposed that “foreign” cells were attacking women’s and children’s tissues. A series of surprises weakened this hypothesis; microchimeric cells seem to be innocuous in some cases, and perhaps even beneficial in others. In one article title, Lee Nelson asks whether microchimeric cells are “protectors” or “insurgents”. Both tropes – the nefarious immigrant and the productive, assimilated worker – are available as modern Western motifs. This is not to say that the scientists themselves were xenophobic and became cosmopolitan overnight. Rather, they recast their observations in familiar geopolitical terms, but the anthropomorphized cells were allowed different – more worldly – possibilities.
SD: Finally, both the idea of 'foreign' and 'migrant' cells suggest a splitting of self and other. You propose to transcend this by reframing the maternal-foetal relationship and the 'borders' of bodies. Could you explain this proposition?
AM: My proposal follows other writers – some of them scientists I’ve interviewed, many of them feminists – who challenge the mutually reinforcing ideas of autonomous selves and defended nation-states. Importantly, this challenge is led by the liveliness of biological bodies that defy containment. Alternatives tend to highlight similitude instead of difference, relationality rather than independence, and interspersion rather than purity. In pregnancy, these alternatives render the sovereign fetus an unthinkable entity.
Simon Dawes is Editor of the TCS Website and Editorial Assistant to Theory, Culture & Society and Body & Society
You can access Aryn’s article ‘Microchimerism in the Mother(land): Blurring the Borders of Body and Nation’ and the rest of the articles in Body & Society’s Special Issue on Bodily Integrity (vol.16, issue 3) here
TCS and B & S are published by SAGE.