To determine whether microchimerism can be implicated in Sjögren's syndrome (SS) by studying minor salivary glands, one of the targets of the disease.
Labial salivary gland (LSG) biopsy specimens from 16 female patients with primary SS and 11 with systemic sclerosis (SSc) (a disease in which microchimerism is frequently detected) were analyzed. All 27 women had a history of pregnancy with a male baby. Specimens were microdissected, and polymerase chain reaction (PCR) was performed using the unique sex-determining region Y gene probe.
The sensitivity of PCR for detecting male cells in LSG was high; the presence of 3 male cells was consistently detected in DNA extracted from a normal female LSG specimen to which male DNA had been added, and 1 male cell was detected in 50% of specimens analyzed. Male DNA was not found in any of the specimens from the 16 SS patients but was detected in 5 (45%) of 11 SSc specimens (P = 0.006). No differences in the rate of detection were found between patients with diffuse and limited SSc (male DNA detected in 2 of 3 and 3 of 8, respectively; P = 0.55) or between patients with and those without secondary SS (1 of 6 and 4 of 5, respectively; P = 0.08).
The results of our study strengthen the possibility that microchimerism is implicated in SSc. This is the first study to demonstrate the presence of chimeric cells in LSG from 45% of SSc patients, independent of the presence of secondary SS. However, microchimerism was not detected in LSG from patients with primary SS, suggesting that the pathogenesis of the 2 diseases is different.