Immunophenotypic Characterization of Citrate-Containing A Concentrates in Maintenance Hemodialysis: A Pre-Post Study

Introduction

Due to chronic inflammation, maintenance hemodialysis (MHD) patients continue to show excess mortality. Acetate-free citrate-buffered A concentrates could be a way to improve the biocompatibility of the procedure, reduce chronic inflammation, and thus in the long term improve the prognosis of patients.

Methods

Using a pre-post design (3 months of acetate followed by 3 months of citrate-acidified A concentrates in standard bicarbonate-based dialysate hemodialysis, CiaHD) and linear mixed model analysis in 61 stable HD patients, we assessed the impact of CiaHD on counts and phenotypes of peripheral T cells and monocytes by flow cytometry.

Results

Switching to CiaHD left C-reactive protein (CRP) levels and leucocyte counts unaffected. However, CiaHD increased lymphocyte counts ex vivo. Furthermore, we found a decrease in total CD3+CD4+CD69+ ((109/L), mean ± SD: acetate, 0.04 ± 1.0 versus citrate, 0.02 ± 0.01; P = 0.02) activated cells, while the number of CD28+ T cells remained stable. No differences were noted regarding T-cell exhaustion marker expression, CD14+CD16+ monocyte counts, and PMN-MDSCs.

Conclusion

Compared with acetate, CiaHD has a minor impact on lymphocyte counts and CD4+T-cell activation, which was independent of systemic CRP and ionized magnesium, calcium levels, and other dialysis prescription modalities.

[SARS-CoV-2 mRNA-based vaccine in hemodialysis patients: a single center-experience]

Hemodialysis patients have an increased risk of severe complications when infected with SARS-CoV-2. The introduction of the SARS-CoV-2 vaccine represented an important progress in limiting severe forms of the disease. The focus of our study is the detection of the antibody titer in chronic hemodialysis patients vaccinated with the mRNA vaccine BNT162b2 (Comirnaty, Pfizer-BioNTech). The antibody titers were measured in 57 hemodialysis patients, vaccinated with 3 doses according to ministerial criteria, by ElectroChemiLuminescence ImmunoAssay (ECLIA). The response was defined as an antibody titer above the dosable level > 0,8 UI/ml. A good antibody response was defined as titer > 250 UI/ml. Infections with SARS-CoV-2 and adverse effects to the vaccine were recorded. Our study showed in 93% of the hemodialysis patients a dosable antibody response after the second dose of the vaccine. After the third dose of the vaccine, 100% of the hemodialysis patients reached a dosable antibody titer. The vaccine proved to be safe, no serious adverse events were observed. After the third dose, SARS-CoV-2 infections were still observed, but with reduced severity. A vaccination course against SARS-CoV-2 infection with three doses of BNT162b2 in the dialysis patient is associated with a good immune response and protects against severe infections.

MO739EX VIVO THROMBOCYTE FUNCTION IN HEMODIALYSIS PATIENTS

Background and Aims

Coagulation disorders with both risk for bleeding and thrombotic events are common in hemodialysis (HD) patients. Altered thrombocyte counts and function may account for that. Here, we sought to better characterize thrombocyte function in hemodialysis patients.

Method

Platelet function was investigated using the Multiplate analyzer (Roche) based on impedance aggregometry. Adenosine diphosphate (ADP) was used to induce platelet aggregation and area under the curve (AUC) was used as primary endpoint. Platelet counts and C-reactive protein (CRP) levels were measured. Hospitalization was the primary clinical outcome. Pearson regression was used to test for associations of thrombocyte function and the primary endpoint.

Results

In total 60 chronic HD patients undergoing dialysis 3 times per week, and 67 healthy controls were included. In general, HD patients presented with significantly lower thrombocyte numbers compared to healthy controls (Median: 221 vs. 245 G/l, p=0.029). Further, thrombocyte function as determined by AUC was significantly altered in HD patients versus healthy controls (Median: 455 vs. 677 AU*min, p<0.001; figure 1) with a significant correlation for platelet count and platelet function (r=0.42, p=0.001).

Platelet function also correlated with the inflammatory state as seen by systemic CRP levels (r=0.28, p=0.033). Regarding the clinical outcome, platelet function correlated with hospitalization rates for infectious disease (r=0.27; p=0.040) and cardiovascular events (r=0.30; p=0.022). In case of hospitalization rates for infectious disease this correlation remained stable irrespective of adjustment for thrombocyte counts (r=0.27, p=0.036).

Conclusion

Lower platelet counts and altered function in HD patients was associated with risk of hospitalization and markers of inflammation in this cohort. The Multiplate analyzer appeared to be a valid and easily accessible method to assess thrombocyte function. Further studies are needed to determine whether assessment of thrombocyte function in clinical routine should be used to stratify risk in the vulnerable population of HD patients.