Immunology

Immunophenotypic tests for children and adults are carried out in the Department of Immunology using high-performance 10-color/3-laser flow cytometers. In addition to patient care, a broad spectrum of validated flow cytometric examinations is also offered within the framework of clinical studies (phase I-III). Depending on the problem, advice is also offered on the establishment and validation of new flow cytometric panels.

These examinations are important for many clinical questions:

• if a congenital cellular immunodeficiency is suspected (SCID, MHC or TAP defects, hyper-IgM syndrome, leukocyte adhesion defect)
• for the classification of patients with variable immunodeficiency (CVID)
• if immune dysregulation is suspected (monitoring of interferonopathies using Siglec-1)
• in case of suspected granulocyte dysfunction (phagocytosis, O2 radical formation)
• for immune monitoring of acquired cellular immunodeficiencies (CD4 T cell count and CD4/8 ratio in HIV infection, therapy monitoring under immunosuppression/chemotherapy)
• for immune monitoring in intensive care patients (e.g. identification of patients at risk by assessing immunocompetence)
• for immune monitoring of transplanted patients (suspected rejection, viral infection, therapy monitoring immunosuppression)
• if autoimmune processes are suspected (T-cell activation)
• to assess therapy efficacy (e.g. B-cell count under rituximab therapy)
• in Sezary syndrome (assessment of CD7 and CD26 expression on CD4 T cells)
• if a monoclonal expansion of B or T lymphocytes is suspected
• for the assessment of thymus function in persistent T-lymphopenia
• to assess the frequency of regulatory T lymphocytes
• to assess the frequency of naive, effector and memory T cells in transplanted and/or immunosuppressed patients

The Department of Immunology offers numerous functional tests of the immune system, which are of particular interest for the following questions.

If a functional T-cell defect is suspected (frequently recurrent or severe viral or fungal infections, infection with atypical mycobacteria), the following tests are useful:

• Lymphocyte transformation test (assessment of lymphocyte proliferation after stimulation with mitogens)
• Determination of Th1/Th2/Th17 cytokine production
• Phosphorylation assay of intracellular STAT molecules for suspected cytokine receptor defects or neutralizing cytokine autoantibodies
• If granulocyte function is suspected to be impaired (septic granulomatosis/CGD, frequent/severe purulent bacterial infections), the following tests are recommended:
  • Phagoburst test (intracellular oxygen radical formation)
  • Leukocyte adhesion defect 1/2 Diagnostics

The quantitative determination of cytokines after stimulation with various receptor ligands is indicated for the following questions:
Suspected TLR defect, suspected IL-1β/TNFα receptor defect (frequently recurrent severe bacterial infections)
Monitoring of iatrogenic immunosuppression

In the case of recurrent or severe infections with atypical mycobacteria or Salmonella, a possible type 1 pathway defect (IFNγ or IL-12 synthesis or receptor defects) should be investigated or it should be checked whether cytokine autoantibodies are present.

Advanced diagnostics in patients with immunoglobulin synthesis disorders (variable immunodeficiency, CVID) includes the assessment of CD40L and ICOS expression on CD4+ T cells after mitogen stimulation using FACS.

Soluble mediators in plasma, serum, urine or cerebrospinal fluid are measured using a fully automated chemiluminescence immunoassay system, sandwich ELISA, or multiplex immunoassays.

Chemiluminescence assay

The following parameters are measured on the Immulite 1000:
TNFα, IL-1β, IL-6, IL8, IL-8 total (after erythrocyte lysis), IL-10, sIL-2R, LBP.

The quantitative determination of these parameters in plasma/serum is indicated for the following questions or diseases, among others:

• inflammatory processes / local and infections
• Autoimmunopathies (e.g. sarcoidosis)
• Graft rejection
• Tumor diseases
• Differentiation between viral/bacterial infections

Cytokines from other materials can also be analyzed for specific questions, for example:

• IL-6 from urine (rejection marker after kidney transplantation)
• IL-6 and IL-10 from intraocular fluid (suspected intraocular lymphoma)
• sIL-2R from cerebrospinal fluid (suspected neurosarcoidosis)
• For the differential diagnosis of dementia, the dementia markers p-TAU, TAU, beta-amyloid 1-40 and 1-42 are determined on the Fujirebio Lumipulse G660II immunoassay analyzer.

Sandwich ELISA

The following parameters are determined using sandwich ELISA:

• MBL (mannose-binding lectin) for susceptibility to infections, especially frequent recurrent respiratory infections
• Tetanus toxoid IgG, total pneumococcal polysaccharide IgG and IgG2, for example in vaccination response monitoring and for diagnosing CVID
• IL-1RA (interleukin-1 receptor antagonist – anti-inflammatory cytokine), if increased in the context of systemic inflammatory reactions / sepsis
• Quantiferon-TB-Gold test (for infection diagnostics)
• SEB-induced IL-17 (see functional tests)
• NF-L (neurofilament light chain) in case of a neurodegenerative disease such as ALS
• S100 A8/9 (calprotectin) in serum

Multiplex Immunoassays

Multiplex immunoassays enable the simultaneous analysis of several analytes in a small sample volume (usually 50 µl). With the electrochemiluminescence technology from Meso Scale Discovery and the cytokine bead arrays (BD Biosciences), the laboratory offers two platforms for multiplex analysis.

The standard offer includes a broad panel of cytokine diagnostics (e.g. for suspected T-cell dysfunction, cytokine defects, allergic disposition). Contract measurements can also be carried out according to special customer requirements.

Digital immunoassay platform

The Quanterix SIMOAÒ (single molecule array) platform is a new digital immunoassay technology platform with up to 1,000-fold higher sensitivity compared to conventional ELISAs. With the help of this technology, neuronal biomarkers such as neurofilament light chain (NF-L), which are usually determined in cerebrospinal fluid, can now also be measured in serum despite their low concentration. This enables the expansion of NF-L determination after simple blood sampling in many areas of outpatient and inpatient neurological and psychiatric patient care. Labor Berlin has introduced this technology into routine diagnostic care throughout Europe as an ISO 15189 accredited test.

The infection diagnostics offered include the following examinations:

• Quantiferon TB Gold test: for suspected infection with Mycobacterium tuberculosis (TBc)