In addition to the detection of specific and ideally also neutralising antibodies, which are assigned to the B-cell-mediated immune response, there is another examination method that provides decisive information about the second branch of immunity, namely the T-cell-mediated one. This is examined classically, also in our laboratory using ELISpot. The T-cells often still form a reliable defence front even when the antibodies have slowly degraded below the detection limit over time. The ELISpot method presents T cells with a specific antigen and measures their response to it. We test with CE-certified specific SARS-CoV antigen and in parallel with PanCorona antigen to exclude possible cross-reactivity with endemic human coronaviruses.
In order to protect the lymphocytes, we ask for the shortest possible transport routes and times of the patient material for T-cell mediated immunity. When sending the samples, please note that they should arrive on Tuesdays and Wednesdays to allow for processing.
We are happy to carry out the required blood collection for T-cell immunity on Tuesdays and Wednesdays from 10:15-11:00 at our laboratory (mobile office).
Information for doctors and medical professionals:
To perform the T-cell test (ELISpot), 24 ml of anticoagulated blood (3 lithium heparin tubes) are required. Please note that the time span between blood collection and arrival at the laboratory should not exceed 20 h and that the sample should be kept at room temperature during this time!
Peripheral blood mononuclear cells (PBMCs, including lymphocytes) are isolated from this sample in our laboratory and cultivated in a 20 h incubation with peptides of the SARS-CoV-2 virus and the peptides of the four endemic human nonSARS corona strains. During this incubation, an authentic immune response occurs with production of interferon-γ, which can be considered as an indicator of a specific T cell response. The selected addition of peptides, for example of S 1 and other viral proteins, allows a precise statement about the effective cellular immunity after natural COVID-19 infection and/or after vaccination against SARS-CoV-2.
The interferon-γ production by T-lymphocytes in contact with spike protein 1 (S 1) versus other viral peptides is measured. The measured value is given quantitatively as the number of producing T cells (stimulation index).
