Microchimerism in labial salivary glands of hematopoietic stem cell transplanted patients

Microchimerism has been extensively investigated in autoimmune diseases, which display similarities with graft-vs-host disease. This study was conducted to investigate the presence of microchimerism in minor salivary glands of hematopoietic stem cell transplanted patients, one of the targets of graft-vs-host disease.

Labial salivary glands biopsy specimens from 11 stem cell transplanted patients were analysed. The samples were grouped in control (five specimens from a female-to-female transplantation) and study group (five glands from male-to-female transplantation). One male transplanted patient was used as a positive control. Fluorescence in situ hybridization with Y-chromosome probe and immunofluorescence with anticytokeratin AE1/AE3 and CD45 were used to identify Y-chromosome positive glandular epithelial cells from allogeneic hematopoietic stem cell transplanted patients.

In the study group, all samples were positive to Y-chromosome and cytokeratin AE1/AE3, in agreement with the pattern exhibited by male labial salivary gland. None of the samples from control group were positive to Y-chromosome despite being positive to cytokeratin AE1/AE3. Positivity to CD45 was not relevant.

Microchimerism in the labial salivary glands of sex-mismatched stem cell transplanted patients is a real phenomenon. Further studies are necessary to elucidate the impact of this phenomenon on the clinical status of stem cell transplanted patients.