Evidence of fetal microchimerism in Hashimoto's thyroiditis

Fetal microchimerism, the engraftment of fetal progenitor cells into matern al tissues, has been implicated in the etiology of autoimmune diseases. We used PCR analysis to determine whether microchimerism occurred in the thyro id glands of female patients suffering from Hashimoto's disease and thus ma y be involved in its etiology. PCR amplification was performed from thyroid gland specimens using primers unique to a Y-chromosomal sequence (SRY gene ) and primers for a sequence that is Y/X-chromosomal homologous except for a 6-bp deletion in the X-chromosomal sequence (amelogenin). microchimerism was detected in 8 of 17 Hashimoto patients, but in only 1 of 25 controls (n odular goiters). Both groups were of similar age and had comparable numbers of pregnancies and numbers of sons. All individuals with microchimerism ha d given birth to at least 1 son. Our results show that microchimerism is si gnificantly more common in Hashimoto patients than in patients suffering fr om nodular goiter. We therefore suggest that microchimerism might play a ro le in the development of Hashimoto's disease, although we cannot completely eliminate the hypothesis that microchimerism is just an "innocent bystande r" in a process triggered by other mechanisms.