CLINICAL STUDY Fetal microchimerism in Hashimoto’s thyroiditis: a quantitative approach

Objective: Fetal microchimerism (MCH) has been implicated in the etiology of autoimmune diseases such as autoimmune thyroiditis. The goal of the study was to reliably estimate the number of fetal engrafted cells and to further investigate factors influencing the development of MCH. Methods: Quantitative real-time PCR amplification using Y-chromosome specific (DYS14) and autoso-mal (b-globin) loci was performed on thyroid gland specimens. Furthermore, we compared the distri-bution of ABO and rhesus systems in mothers with and without blood MCH in relation to the blood groups of the children. Results: MCH was detected in eight of 21 Hashimoto patients in a frequency range of 15 to 4900 male cells per 100000 total cells (median 97 cells), but in none of 17 healthy thyroid glands. In a third group, consisting of 18 nodular goiters, only one sample was positive (182 male cells/100000 total cells). No woman who had not had a prior pregnancy with a male fetus showed MCH. Mothers both with and without MCH showed the same rate of mother/child incompatibilities for the ABO and rhesus systems. Conclusions: The percentage of microchimeric cells varies to a great extent in Hashimoto’s thyroiditis