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

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.

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.

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.

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).