Significance of mast cell renal infiltration in patients with anti-GBM nephritis.

To investigate the role of mast cells (MCs) renal infiltration in the progression of human anti-GBM nephritis, 38 patients diagnosed with anti-GBM nephritis were enrolled. Renal biopsies were performed. Immunohistochemistry was conducted to detect MCs in renal tissues. Patients were divided into group 1 (MCs <50 mm(-2), n = 18) and group 2 (MCs ≥50 mm(-2), n = 20) according to the infiltrating renal MC count. The clinical-pathological indices were compared. And, correlation between MCs and the clinical-pathological indices was analyzed. Patients of group 2 had more severe renal dysfunctions, expressed as higher levels of serum creatinine (SCr 8.95 ± 3.66 vs. 4.75 ± 2.73 mg/dL, p < 0.001), urine retinol-binding protein (RBP 29.8 ± 13.9 vs. 15.7 ± 11.5 mg/dL, p = 0.005), and lower urinary osmotic pressure. Pathologically, patients of group 2 had a higher percentage of fibrous/fibrocellular crescents (66.7 ± 21.9 vs. 47.0 ± 33.6%, p = 0.037) but a lower percentage of cellular crescents. More CD8 (268 mm(-2) vs. 180 mm(-2), p = 0.045) and CD68 (268 mm(-2) vs. 180 mm(-2), p = 0.045) positive cells infiltrating the interstitium were observed in group 2. Furthermore, renal MCs correlated significantly with the total number of crescents and the tubular interstitial CD8 and CD68 positive cells. And, the number of MCs was associated with the histological types. The renal function was significantly different between the two groups at presentation. However, at 3 and 6 month follow-up, the patient outcome was associated with the histological types. Our study showed that MC infiltrations were associated with chronic lesions in anti-GBM nephritis and may be involved in the loss of renal function with pathological changes.