Fetal microchimerism in kidney biopsies of lupus nephritis patients may be associated with a beneficial effect

Greiciane MS Florim, Heloisa C Caldas, Julio CR de Melo, Maria Alice SF Baptista, Ida MM Fernandes, Marcela Savoldi-Barbosa, Gustavo H Goldman, Mario Abbud-Filho

Microchimeric male fetal cells (MFC) have been associated with systemic lupus erythematosus and reports have further correlated MFC with lupus nephritis (LN). In the present study, we evaluated the frequency of MFC in the renal tissue of LN patients. Twenty-seven renal biopsies were evaluated: 14 from women with clinical and laboratory findings of LN and 13 from controls. Genomic DNA was extracted from kidney biopsies and the male fetal DNA was quantified using real-time quantitative polymerase chain reaction for the detection of specific Y chromosome sequences. MFC were detected in 9/14 (64%) of LN patients while no MFC were found in the control group (P = 0.0006). No differences in the pregnancy history were found between LN and the control group. Significantly higher amount of MFC were found in LN patients with serum creatinine ≤ 1.5 mg/dL. Furthermore, women with MFC had significantly better renal function at the time of biopsy (P = 0.03). In contrast, LN patients without MFC presented with more severe forms of glomerulonephritis (class IV = 60% and V = 40%). Our data indicate a high prevalence of MFC in renal biopsy specimens from women with LN, suggesting a role for MFC in the etiology of LN. The present report also provides some evidence that MFC could have a beneficial effect in this disease.