Variables associated to fetal microchimerism in systemic lupus erythematosus patients.

In the present study, we sought to identify the factors during the pregnancy of systemic lupus erythematosus (SLE) patients that could be linked to the presence and proliferation of male fetal cells (MFC) and the possible relation between these factors and development of lupus nephritis (LN). We evaluated 18 healthy women (control group) and 28 women affected by SLE. Genomic DNA was extracted from peripheral blood and quantified using the technique of quantitative real-time polymerase chain reaction (qPCR) for specific Y chromosome sequences. The amount of MFC was significantly higher in the SLE group compared with the controls (SLE 252 ± 654 vs control 2.13 ± 3.7; P = 0.029). A higher amount of MFC was detected among multiparous SLE patients when compared with the control group (SLE 382 ± 924 vs control 0.073 ± 0.045; P = 0.019). LN was associated with reduced amount of MFC (LN 95.5 ± 338 vs control 388 ± 827; P = 0.019) especially when they have delivered their child before age 18 (LN 0.23 ± 0.22 vs control 355 ± 623; P = 0.028). SLE patients present a higher amount of MFC, which may increase with the time since birth of the first male child. LN patients showed an inverse correlation with MFC, suggesting that the role of the cells may be ambiguous during the various stages of development of the disease.