Neutrophil activation in immunoadsorption

Automated, Point-of-Care mobile flow cytometry: Bringing the laboratory to the sample

Background

Innate effector cells are very responsive to infectious and inflammatory cues found in damaged and inflamed tissues. Their activation is a potential target to assess the state of the immune system. Unfortunately, these cells are very susceptible for ex-vivo activation, hampering accurate interpretation of flow cytometry data. Whether a brief window exists before ex-vivo activation starts to occur is currently unknown.

Aims

1) This study extensively investigated ex-vivo activation of innate effector cells over time. 2) We tested the feasibility of applying a mobile, automated, flow cytometry laboratory for out-of-hospital Point-of-Care analyses to minimize ex-vivo activation bias.

Methods

1) Ex-vivo neutrophil, eosinophil and monocyte activation in a blood collection tube over time and the reactivity to a formyl-peptide was investigated in a healthy cohort. 2) To facilitate fast, out-of-hospital analysis, application of the mobile flow cytometry was tested by placing an automated flow cytometer into a van. The stability of the setup was assessed by repetitively measuring laser alignment and fluorescence verification beads.

Findings

1) Immediately after venipuncture activation marker expression on neutrophils, eosinophils and monocyte subsets started to change in a time-dependent manner. 2) The mobile flow cytometry laboratory travelled over 3000 km, performing measurements at 19 locations with a median single-person-set-up time of 14 min. The laser alignment and fluorescence were stable during all experiments.

Conclusions

Accurate flow data of innate immune cells are only obtained when ex-vivo activation is kept to minimum. The use of a mobile, fast, automated, flow cytometry laboratory for out-of-hospital Point-of-Care analyses provides new investigational and diagnostic possibilities outside major hospital flow cytometry laboratories.

Neutrophil and Eosinophil Responses Remain Abnormal for Several Months in Primary Care Patients With COVID-19 Disease

Introduction

Neutrophil and eosinophil activation and its relation to disease severity has been understudied in primary care patients with COVID-19. In this study, we investigated whether the neutrophil and eosinophil compartment were affected in primary care patients with COVID-19.

Methods

COVID-19 patients, aged ≥ 40 years with cardiovascular comorbidity presenting to the general practitioner with substantial symptoms, partaking in the COVIDSat@Home study between January and April 2021, were included. Blood was drawn during and 3 to 6 months after active COVID-19 disease and analyzed by automated flow cytometry, before and after stimulation with a formyl-peptide (fNLF). Mature neutrophil and eosinophil markers at both time points were compared to healthy controls. A questionnaire was conducted on disease symptoms during and 3 to 6 months after COVID-19 disease.

Results

The blood of 18 COVID-19 patients and 34 healthy controls was analyzed. During active COVID-19 disease, neutrophils showed reduced CD10 (p = 0.0360), increased CD11b (p = 0.0002) and decreased CD62L expression (p < 0.0001) compared to healthy controls. During active COVID-19 disease, fNLF stimulated neutrophils showed decreased CD10 levels (p < 0.0001). Three to six months after COVID-19 disease, unstimulated neutrophils showed lowered CD62L expression (p = 0.0003) and stimulated neutrophils had decreased CD10 expression (p = 0.0483) compared to healthy controls. Both (un)stimulated CD10 levels increased 3 to 6 months after active disease (p = 0.0120 and p < 0.0001, respectively) compared to during active disease. Eosinophil blood counts were reduced during active COVID-19 disease and increased 3 to 6 months after infection (p < 0.0001). During active COVID-19, eosinophils showed increased unstimulated CD11b (p = 0.0139) and decreased (un)stimulated CD62L expression (p = 0.0036 and p = 0.0156, respectively) compared to healthy controls. Three to six months after COVID-19 disease, (un)stimulated eosinophil CD62L expression was decreased (p = 0.0148 and p = 0.0063, respectively) and the percentage of CD11bbright cells was increased (p = 0.0083 and p = 0.0307, respectively) compared to healthy controls.

Conclusion

Automated flow cytometry analysis reveals specific mature neutrophil and eosinophil activation patterns in primary care patients with COVID-19 disease, during and 3 to 6 months after active disease. This suggests that the neutrophil and eosinophil compartment are long-term affected by COVID-19 in primary care patients. This indicates that these compartments may be involved in the pathogenesis of long COVID.

Changes of selected hematologic parameters during long-term immunoadsorption therapy

Changes of selected hematologic parameters were studied in six patients treated with immunoadsorption for myasthenia gravis. The mean duration of therapy was 18.6months; 245 procedures were performed in total. Before and after each procedure the full blood count was examined. A decrease was noted in the hemoglobin concentration (median -7.27%) and in platelet count (median -5.63%) after each procedure. On the other hand, an increase in leukocyte count was noticed after each procedure (median 6.63%). However, in three patients, it was observed that with increasing numbers of procedures, the leukocyte count rises were lower during long-term treatment. We suppose that the decrease in hemoglobin concentration was induced both by the large volume of blood samples collected for laboratory testing and by the residual volume of blood which remains in the tubing. From the continuous decrease in leukocyte count after long-term treatment with immunoadsorption in our three patients, it may be concluded, that some type of immunomodulatory effect (immunosuppression) is involved.

Acute glomerulonephritis occurring during immunoadsorption with staphylococcal protein A column (Prosorba(R))

BACKGROUND

Apheresis of patient plasma by immunoadsorption with a staphylococcal protein A (SPA) column is used in a variety of autoimmune disorders. Leukocytoclastic vasculitis is an uncommon severe complication that can occur during immunoadsorption with SPA (Prosorba.

METHODS

We report a case of immune complex glomerulonephritis occurring during Prosorba immunoabsorption in a patient with rheumatoid arthritis (RA). Using a Medline literature search and information provided by Cypress Bioscience/Fresenius Hemocare, we review renal complications associated with Prosorba immunoadsorption.

RESULTS

We identified seven additional potential cases of glomerulonephritis (GN) in association with Prosorba immunoadsorption. Five of these patients were being treated for RA, and two for idiopathic thrombocytopenia purpura (ITP). Renal biopsies were performed on four patients, all of whom had evidence of immune complex GN. Among RA patients treated with Prosorba, the incidence of GN closely paralleled that of leukocytoclastic vasculitis at 1.75%. The presence of leukocytoclastic vasculitis was a significant risk factor for the development of GN (relative risk = 75.95, CI 7-1869, P = 0.00021). In contrast, among more than 10 000 ITP patients treated with Prosorba, there were only two potential cases of GN. The risk of developing GN in association with Prosorba immunoadsorption was significantly greater for patients with RA than for those with ITP (relative risk = 62.95, CI 10-453, P = 0.00002).

CONCLUSION

This case series highlights the risk of GN among patients undergoing SPA immunoadsorption. The development of GN is associated with the presence of leukocytoclastic vasculitis. Patients with RA seem to be at particular risk.