Flow cytometry-based diagnostic approach for inborn errors of immunity: experience from Algeria

Area of Science:

• Clinical Immunology
• Diagnostic Pathology
• Medical Laboratory Science

Background:

• Inborn errors of immunity (IEIs) are a heterogeneous group of genetic disorders affecting the immune system.
• Accurate and timely diagnosis is crucial for effective management and improving patient outcomes.
• Flow cytometry (FCM) offers a powerful platform for evaluating immune cell populations and functions.

Purpose of the Study:

• To retrospectively review the utility of flow cytometry (FCM) in diagnosing inborn errors of immunity (IEIs).
• To present practical, FCM-based diagnostic approaches tailored to various clinical scenarios.
• To share experience from a single center in Algeria, highlighting its applicability in diverse settings.

Main Methods:

• Retrospective review of pediatric and adult patients with suspected immunodeficiency.
• Application of FCM for lymphocyte subset analysis, protein expression, and functional assays.
• Analysis of diagnostic yield for 70 different IEIs across 9 categories.

Main Results:

• FCM was utilized in the diagnosis of 670 patients over a nearly seven-year period.
• A total of 514 patients (76.7%) received diagnoses or supportive evidence for IEIs via FCM.
• FCM provided direct diagnoses for conditions like SCID and MHC class II deficiency, and suggestive evidence for others, guiding genetic testing.

Conclusions:

• Flow cytometry is a highly valuable and cost-effective method for diagnosing most IEIs.
• FCM is particularly relevant in low-income countries with limited access to genetic testing.
• FCM analysis provides direct diagnostic insights, suggests underlying genetic defects, and aids in gene prioritization for IEIs.