Background. Some clinical cases of long-term COVID-19 have been reported, which can be caused by micro- and macrothrombotic complications that persist after recovery. Although more information has been gathered on coagulation disorders during COVID-19, the post-COVID-19 period is unknown. Fibrinogen and D-dimer are the primary parameters for detecting an imbalance in the conversion of soluble fibrinogen and the cleavage of insoluble fibrin clots. Clinical data describe higher concentrations of fibrinogen and D-dimer that may lead to COVID-19 coagulopathy in ill patients [1, 2].
The aim of our research was to establish the concentration of fibrinogen and D-dimer in donor groups who recovered from COVID-19 depending on the titers of anti-SARS-CoV-2 IgG in the blood plasma.
Materials and methods. People who had suffered from COVID-19 agreed to be donors of blood plasma for biotechnological purposes at the "BIOPHARMA-PLASMA" company (Kyiv, Ukraine). Blood plasma was collected from donors who had recovered from COVID-19 3-6 months ago. Donors were checked by screening tests before blood plasma was used to produce targeted biotechnological drugs. We were sent the blood plasma of donors with determined anti-SARS-CoV-2 IgG titers for scientific research. The Abbott SARS-CoV-2 IgG serological assay was used to determine the titers of anti-SARS-CoV-2 IgG in blood plasma. We had donor groups with anti-SARS-CoV-2 IgG titers: 0 (n = 20), 10 ± 3 (n=20), 55 ± 5 (n=20), 65 ± 5 (n=20), 75 ± 5 (n=20), 85 ± 5 (n=20), 95 ± 5 (n=20), 125 ± 5 (n=20) and 175 ± 5 (n=20) Index (S/C). The concentration of fibrinogen was measured by the Clauss method. The concentration of D-dimer was determined by sandwich-type immunochemiluminescent assay using the D-dimer Test Kit for CLIA Maglumi (Snibe Co., Ltd., China).
Results. We examined the coagulation parameters in each donor group. We then identified the maximum and minimum concentrations of fibrinogen and D-dimer among donor groups with titers of anti-SARS-CoV-2 IgG ≥ 10 ± 3 Index (S/C). The donor group with titer of anti-SARS-CoV-2 IgG 0 Index (S/C) was chosen as a reference point.
We found that all donor groups with titers of anti-SARS-CoV-2 IgG ≥ 10 ± 3 Index (S/C) had higher concentrations of fibrinogen and D-dimer than in donors with titer – 0 Index (S/C).
The maximum concentration of fibrinogen was characterized for the donor group with titer of anti-SARS-CoV-2 IgG 10 ± 3 Index (S/C) that was higher by 107.4% than in donors with titer - 0 Index (S/C). The minimum was determined in donor group with titer of anti-SARS-CoV-2 65 ± 5 Index (S/C), which was an increase by 32.1% than in donors with titer - 0 Index (S/C), Table 1.
| Donor group with titer of anti- SARS-CoV-2 IgG, Index (S/C) | Concentration of fibrinogen, mg/dL |
|---|---|
| 0 | 238.70 ± 37.12 |
| 10±3 | 495.13 ± 52.04 |
| 65±5 | 315.24 ± 36.09 |
The maximum concentration of D-dimer was demonstrated in donor group with titer of anti-SARS-CoV-2 IgG 55 ± 5 Index (S/C) that was increase by 440% than in donors with titer - 0 Index (S/C). The minimum was defined in donors with titers - 85 ± 5 and 175 ± 5 Index (S/C). Both had an increase of concentration D-dimer by 120% than in donors with titer - 0 Index (S/C), Table 2.
| Donor group with titer of anti- SARS-CoV-2 IgG, Index (S/C) | Concentration of D-dimer, μg·FEO/L |
|---|---|
| 0 | 0.10 ± 0.05 |
| 55±5 | 0.54 ± 0.20 |
| 85±5 | 0.22 ± 0.06 |
| 175±5 | 0.22 ± 0.06 |
Conclusion. Our study focused on detecting key changes in coagulation parameters depending on the titers of anti-SARS-CoV-2 IgG. According to the described results, we may confirm the defect of the coagulation profile in donor groups with titers of anti-SARS-CoV-2 IgG ≥ 10 ± 3 Index (S/C). Therefore, it is necessary to carry out the additional in vitro and in vivo research with purified anti-SARS-CoV-2 IgG.