HLA-DR expression and apoptosis: a cross-sectional controlled study in hemodialysis and peritoneal dialysis patients

Abstract

Background: Altered HLA-DR expression and apoptosis have been described to reflect a state of immunological dysfunction in uremia. Here, we performed a cross-sectional, controlled study to evaluate monocyte HLA-DR expression and apoptosis in dialyzed chronic kidney disease patients.

Methods: Monocyte HLA-DR expression was determined in 81 hemodialysis (HD) and 51 peritoneal dialysis (PD) patients and 40 healthy controls. By triple-color flow cytometry, we analyzed the percentage of monocytes in whole blood, the percentage of HLA-DR+ monocytes and the mean fluorescence intensity. Using U937 cell line incubated with the patients' plasma, we analyzed the percentage of apoptosis induced after 96 h.

Results: Both HD and PD patients had lower, but statistically not significant, monocyte HLA-DR expression compared to controls (96.47 +/- 3.83% and 96.64 +/- 3.29% respectively, versus 98.42 +/- 1.05%). However, mean fluorescence intensity of HLA-DR was significantly higher in PD (149.35 +/- 80.96) than in HD (99.20 +/- 40.46), and controls (73.25 +/- 27.78, p < 0.001). Apoptosis was higher in both HD and PD (35.14 +/- 6.77 and 14.37 +/- 5.03%) compared to controls (11.30 +/- 2.03%, p < 0.001), and significantly higher in HD compared to PD.

Conclusion: A reduced inflammatory state and the continuous solute removal in PD may attenuate immune dysfunction in uremia. In HD but not in PD patients, there was a significant correlation between the percentage of HLA-DR+ monocytes with apoptosis (R = 0.230, p = 0.04).