N antiserum to human ig kit series

Cellular immunity was assessed by multicolor flow cytometric determination of surface markers using human monoclonal anti-CD3-fluorescein isothiocyanate (FITC), anti-CD4-phycoerythrin (PE), anti-CD8-allophycocyanin (APC), anti-CD19-PE, anti-CD16-APC, and anti-CD56-PE antibodies (BD Multitest), for determination of proportions and numbers of total T (CD3+), helper T (Th, CD3+CD4+), cytotoxic T (Tc, CD3+CD8+), Natural Killer (NK, CD3-CD16+CD56+), and B (CD3-CD19+) cell subsets. All samples were examined by a BD FACSCanto II Flow Cytometer. Data were analyzed by FlowJo v10.0.
Serum levels of C reactive protein (hypersensitive, hsCRP), immunoglobulin (IgG, IgM, IgA, and IgE), and complements (C3, C4) were detected by rate nephelometry immunoassay (N Antiserum to Human Ig Kit series, Siemens, Germany). The plasma levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ) were detected by Cytometric Bead Array using the human Th1/2 cytokine kit II (BD Ltd., USA). All tests were conducted according to the manufacturer's instructions.

We collected age, gender, initial symptoms, laboratory findings, history of comorbidities, treatments, records of chest computed tomographic (CT) scans, and clinical outcomes from the electronic medical records system by two independent investigators (Cai Yuli and Wang Ye).
The detection procedure of COVID-19 by PCR depended on sputum and throat swab samples was described in our previous study [2 (link)]. cTnI was evaluated by kit from Siemens based on the chemiluminescence immunotechnology. BD FACSCanto II Flow Cytometer was used to assess the proportions and numbers of total CD3⁺ T cells, CD3⁺CD4⁺ T cells, CD3⁺CD8⁺ T cells, CD16⁺CD56⁺ Natural Killer cells (NK cells), and CD19⁺ B cells subsets (BD Multitest). Serum levels of IgG, IgM, IgA, IgE, and complements component (C3, C4) were detected by rate nephelometry immunoassay (N Antiserum to Human Ig Kit series, Siemens, Germany). Cytometric Bead Array with the human helper T cells 1/2 cytokine kit II (BD Ltd., USA) was used to test the plasma levels of cytokines, including interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-10, tumor necrosis factor-α (TNF-α), and γ-interferon. All tests were conducted according to the manufacturer's instructions in routine clinical practices during the COVID-19 pandemic in our hospital.