#3595 DIALYSIS MODALITY AFFECTS SENESCENCE-RELATED PHENOTYPE OF T AND B LYMPHOCYTES

Abstract Background and Aims Hemodiafiltration (HDF) is characterized by enhanced clearance of middle molecular weight toxins and therefore, it is considered superior to hemodialysis (HD), especially in higher hemofiltration volumes. Although proinflammatory cytokines are lower in HDF, its impact on immune phenotype has not been studied, so far. In this study we compared the lymphocytes’ senescent phenotype between HD and HDF patients. Method Senescent and exhausted related lymphocyte markers, including CD45RA, CCR7, CD28, CD57 and PD1 on T cells and CD27 and IgD on B cells, were assessed by flow cytometry in 35 ESRD patients on HD and 25 ESRD patients on HDF of similar age, sex, and ethnicity. Moreover, we evaluated the association of these markers with hemofiltration volume. Results Patients on HDF had significantly reduced CD4+CD28- T lymphocytes, 31(18-74) vs 50(36-131)cells/μL, respectively, p = 0.019, which was restricted only in the CD28-CD57- T cells compartment, [17(9-25) vs 31(19-50)cells/μL, p = 0,002], while terminally differentiated CD28-CD57+ did not differ between the two groups [14(4-49) vs 23(7-52)cells/μL, p = 0,22]. Expression of CD57 molecule on CD4+ T cells depended on dialysis vintage (r = 0.27, p = 0.03). Moreover, HDF patients had lower percentage of CD4+PD1+ exhausted T cells [8.5(6.8-11.7) vs 13.7(8.7-19.5) % for HDF and HD respectively, p = 0.006]. CD8+PD1+ T cells were also lower in HDF patients, without reaching statistical significance [17.4(8.5-41) vs 34(12,7-52.9) % for HDF and HD respectively, p = 0.06]. Hemofiltration volume was negatively correlated to effector memory CD8+ T cells re-expressing CD45RA count (CD8+ EMRA), (r = -0.46, p = 0.027) and positively correlated to total B cells count (r = 0.46, p = 0.025). However, not all B cell subsets were equally affected, with only naïve IgD+CD27- B cells and switched memory IgD-CD27+ B cells count showing positive correlation with hemofiltration volume (r = 0.53, p = 0.008 and r = 0.5, p = 0.015, respectively). Conclusion Hemodiafiltration and high filtration volumes may have beneficial effects on adaptive immunity, predisposing to less senescent and exhausted T and B cell phenotypes.