Toda and colleagues report that microchimerism of fetal cells is uncommon in women with Sjögren's syndrome (SS).1 They performed a nested polymerase chain reaction (PCR) that amplified a Y chromosome-specific sequence to detect male cells in peripheral blood of women who had male offspring to prove the hypothesis that microchimerism can induce Sjögren's syndrome as a manifestation of a chronic graft-versus-host like reaction.

We have also analysed for the presence of the Y chromosome in DNA extracted from peripheral blood nucleated cells of 20 Spanish women with SS (mean age 54.6 years (range 31–77)). These women had male children and were selected from our series of 92 female patients2 who fulfilled four or more of the diagnostic criteria for SS proposed in 1993 by the European Community Study Group. All 20 female patients analysed for the presence of fetal microchimerism were also classified as having definite SS according to the San Diego criteria. A PCR was performed that could detect one male cell in a background of 5×10⁵ female cells. The amount of genomic DNA used in the PCR …

kuwanam{at}sc.itc.keio.ac.jp