Flow cytometry optimizing the diagnostic approach in inborn errors of immunity: experience from Egypt

Abstract

Background Human inborn errors of immunity (IEI) are a group of inherited genetic disorders of the immune system. IEI Patients suffer from severe repeated infections, autoimmunity, lymphadenopathy and/or increased susceptibility to malignancies. IEI are due to absence, disproportion, or loss of function of immune cells; mostly inherited in autosomal recessive manner, hence are more common in countries with high rate of consanguinity. Definite diagnosis of IEI is achieved by genetic analysis, however it is not always available. Aim: to report on different IEI categories and impact of expanding the use of flow cytometry (FCM) in diagnosis, categorization and follow up of IEI patients in a highly consanguineous population. Methods Retrospective chart review on different IEI categories diagnosed at the primary immunodeficiency center in Cairo University Specialized Pediatric hospital from 2011 to 2021 based on expanding the use of FCM. Results 1510 IEI patients were diagnosed; 480 were diagnosed genetically with FMF, 11 with cystic fibrosis and 1019 patients were diagnosed with other IEI disorders. Phagocytic defects were the commonest (30%) followed by severe combined immunodeficiency (22%) and combined immunodeficiency (18.3%). FCM testing properly diagnosed and categorized 73% of the cases. Conclusion Using multi-color FCM to evaluate immune cells populations, subpopulations, functions, and intracellular proteins expression is proved a useful cost-effective method for screening, categorization and follow up of IEI patients. FCM can improve the diagnosis of IEI significantly when tests are properly targeted and well designed. This study presents a 10-year experience in diagnosis of IEI using FCM at a tertiary referral center in a setting of limited resources and yet high prevalence of IEI.

Cluster analysis of flowcytometric immunophenotyping with extended T cell subsets in suspected immunodeficiency

“…In summary, multivariate cluster analysis of a reduced set of immune variables including T‐cell subsets, correctly predicted an individual's immune status (ID vs. No‐ID) in approximately 75% and allowed for visual identification of more severe subentities within the ID group, such as CVID or CID. In keeping with results from other groups, our study supports the use of detailed LFC, including T cell subpopulations, in the work‐up for suspected PID 17,27,28 . This approach is also reflected by the current ESID working definition for the clinical diagnosis of CVID, where total CD4+ and CD4_Naïve need to be assessed 59,60 .…”

“…In keeping with results from other groups, our study supports the use of detailed LFC, including T cell in the work-up for suspected PID. 17,27,28 This approach is also reflected by the current ESID working definition for the clinical diagnosis of CVID, where total CD4+ and CD4_Naïve need to be assessed. 59,60 With the use of online opensource software and a reference data set, cluster analysis may be performed within minutes in the outpatient clinic.…”

“…[17][18][19][20] The results of a recent Egyptian study of more than a thousand pediatric patients support the value of LFC for IEI diagnosis: with a very detailed LFC protocol, including protein expression assays, 73% of patients with an IEI could be diagnosed. 17 Reference values for lymphocyte subsets for different age groups have been published. [20][21][22][23][24][25] Elevation or specific absence of lymphoid cells or proteins within cells detected by flowcytometry of peripheral blood can sometimes suggest a specific IEI entity.…”

“…Also, most genetic studies in PID have a limited diagnostic yield, varying between 15% and 30%, with lower yields in adults 14–16 . Lymphocyte flowcytometry (LFC) of peripheral blood is a readily available diagnostic tool and is becoming increasingly important in diagnosing IEI 17–20 . The results of a recent Egyptian study of more than a thousand pediatric patients support the value of LFC for IEI diagnosis: with a very detailed LFC protocol, including protein expression assays, 73% of patients with an IEI could be diagnosed 17 .…”

“…Lymphocyte flowcytometry (LFC) of peripheral blood is a readily available diagnostic tool and is becoming increasingly important in diagnosing IEI 17–20 . The results of a recent Egyptian study of more than a thousand pediatric patients support the value of LFC for IEI diagnosis: with a very detailed LFC protocol, including protein expression assays, 73% of patients with an IEI could be diagnosed 17 . Reference values for lymphocyte subsets for different age groups have been published 20–25 .…”