Microchimerism

http://en.wikipedia.org/wiki/Microchimerism


This fascinated me...

Relationship with autoimmune diseases and breast cancer

Microchimerism has been implicated in autoimmune diseases. Independent studies repeatedly suggested that microchimeric cells of fetal origin may be involved in the pathogenesis of systemic sclerosis.[1][4] Moreover, microchimeric cells of maternal origin may be involved in the pathogenesis of a group of autoimmune diseases found in children, i.e. juvenile idiopathic inflammatory myopathies (one example would be juvenile dermatomyositis).[5] Microchimerism has now been further implicated in other autoimmune diseases, including systemic lupus erythematosus.[6] Contrarily, an alternative hypothesis on the role of microchimeric cells in lesions is that they may be facilitating tissue repair of the damaged organ.[7]
Moreover, fetal immune cells have also been frequently found in breast cancer stroma as compared to samples taken from healthy women. It is not clear, however, whether fetal cell lines promote the dvelopment of tumors or, contrarily, protect women from developing breast carcinoma.