Objectives: Chimerism indicates the presence of cells from one individual in another, and has been associated with several autoimmune diseases. Chimerism occurs more often in renal tissue of patients with the autoimmune disease systemic lupus erythematosus (SLE) than in normal control kidneys. Although this finding may point towards a role for chimerism in the induction of SLE, it could also indicate that chimerism is the result of repair mechanisms after injury. We performed a post-mortem investigation for the presence of chimerism in 48 organs of 7 women with SLE and established whether there was a relationship between chimerism and injury.
Methods: Chimeric male cells in female tissue specimens were identified through in situ hybridization of the Y-chromosome. Organs were categorized into 4 different groups according to experienced injury. Results were compared to unaffected control organs.
Results: Chimerism was found in all 7 SLE patients. Y-chromosome–positive cells were present in 24 of 48 (50%) organs from women with SLE, which was significantly more than in control organs (P< 0.001). Chimerism occurred more often in organs from SLE patients that experienced injury compared to normal control organs, irrespective of whether the experienced injury was SLE-related, non-SLE-related, or both.
Conclusions: This study for the first time describes the distribution of chimerism in a large number of organs from women with SLE, and demonstrates that the occurrence of chimerism is related to injury. Our data support the hypothesis that tissue chimerism is the result of a repair process.
- systemic lupus eythematosus