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Rapid whole blood flow cytometric test to detect ICOS deficiency in patients with common variable immunodeficiency
Robert Bunk1, Anna-Maria Dittrich, Ilka Schulze
1Institute of Medical Immunology, University Hospital, Campus Charité Mitte, Berlin, Germany.
Insights
A rapid whole blood flow cytometry test effectively analyzes Inducible T-cell Costimulator (ICOS) expression. This method aids in diagnosing ICOS deficiency, a defect seen in common variable immunodeficiency (CVID).
Area of Science:
- Immunology
- Flow Cytometry
- Primary Immunodeficiency
Background:
- Common variable immunodeficiency (CVID) is a heterogeneous primary immunodeficiency.
- Distinct phenotypical abnormalities, including Inducible T-cell Costimulator (ICOS) deficiency, are observed in some CVID patients.
- A rapid whole blood flow cytometry method exists for CD40L deficiency diagnosis.
Purpose of the Study:
- To evaluate the utility of a rapid whole blood flow cytometry method for diagnosing ICOS deficiency.
- To determine if existing CD40L deficiency diagnostic methods are applicable to ICOS deficiency.
Main Methods:
- Whole blood from healthy volunteers and an ICOS-deficient patient was stimulated with PMA and ionomycin.
- ICOS expression was analyzed on CD8-CD3+ lymphocytes using three-color flow cytometry after 4 and 20 hours of stimulation.
Main Results:
- Significant ICOS expression induction was observed on CD8-CD3+ lymphocytes in healthy volunteers after 20 hours of stimulation.
- ICOS upregulation was less pronounced after 4 hours of stimulation.
- No ICOS expression could be induced in lymphocytes from an ICOS-deficient patient.
Conclusions:
- ICOS expression can be reliably analyzed using a rapid whole blood flow cytometric assay.
- This method provides a viable diagnostic tool for ICOS deficiency.
Background/Aims:
Common variable immunodeficiency (CVID) is the most common primary immunodeficiency. With respect to underlying defects it comprises a heterogeneous group of deficiencies. For some patients, distinct phenotypical abnormalities have been described, e.g. partial CD40L deficiency or complete ICOS deficiency. For the diagnosis of CD40L deficiency, a rapid whole blood flow cytometric method has been described several years ago. We aimed to determine if the same method can be used to diagnose ICOS deficiency.
Methods:
Whole blood from 8 healthy volunteers was stimulated for 4 and 20 h with phorbol 12-myristate 13-acetate (PMA) and ionomycin. Induction of ICOS expression was analyzed on CD8-CD3+ lymphocytes using three-color flow cytometry. Blood from a patient with diagnosed ICOS deficiency was also analyzed.
Results:
Whole-blood stimulation with PMA and ionomycin for 20 h resulted in a significant induction of ICOS expression on CD8-CD3+ lymphocytes in healthy volunteers. Four-hour incubation also demonstrated ICOS upregulation but to a much lower extent. In CD8-CD3+ lymphocytes from an ICOS-deficient patient, no ICOS expression could be induced following 20 h of stimulation.
Conclusion:
ICOS expression can be analyzed using a rapid whole blood flow cytometric test.
