Diagnosis of primary immunodeficiency diseases by flow cytometry: Experience from Bangladesh

Abstract

Abstract BACKGROUND: Primary immunodeficiency diseases (PIDDs) are clinically and immunologically diverse and require a wide array of clinical and laboratory modalities to make specific diagnosis. Serum immunoglobulin levels and T cell, B cell and NK (Natural killer) cell immunophenotyping are routine laboratory investigations advised to diagnose the PIDD cases in Bangladesh. Along with T-B-NK markers, use of Naïve (CD45RA+) and memory (CD45RO+) T cell, switched memory B cell (CD27+IgD-) markers, detection of intracellular BTK (Bruton’s tyrosine kinase), LRBA (Lipopolysaccharide-responsive beige-like anchor), DOCK8 (Dedicator of cytokinesis 8) protein expression and DHR123 (Dihydro-rhodamine 123) assay of neutrophil can increase the PIDD cases detection in Bangladesh. METHODS: The study was conducted in the Department of Microbiology and Immunology, Bangabandhu Sheikh Mujib Medical University (BSMMU) during the time period of March, 2021 to February, 2022. Seventy clinically suspected PIDD cases were enrolled in this study on the basis of clinical findings and peripheral venous blood was collected from all patients to perform immunophenotyping. Routine T-B-NK cell, naïve and memory T cell with switched memory B cell markers were detected by flow-cytometry. Serum immunoglobulins (IgG, IgM, IgA & IgE) were estimated by Nephelometry and by Chemiluminescence. Intracellular BTK, LRBA and DOCK8 protein expression was detected by flow-cytometry in suspected X-linked agammaglobulinemia (XLA), LRBA and DOCK8 deficiency patients respectively. DHR123 assay was performed in suspected Chronic granulomatous disease (CGD) patients. RESULTS: Among the 70 clinically suspected PIDD cases, 9 (12.9%) were diagnosed as patients of PIDDs on the basis of laboratory evidence. Five (55.55%) cases were diagnosed as predominantly antibody deficiencies (PADs), 3 (33.33%) were patients of combined immunodeficiency (CID) and 1 (11.11%) was CGD patient. Among the diagnosed PIDD cases, 2 (22.22%) were diagnosed by T-B-NK cell immunophenotyping with serum immunoglobulin levels and 7 (77.77%) cases were diagnosed by additional CD45RA+, CD45RO+, CD27+IgD- markers, BTK protein expression detection and DHR123 assay. LRBA and DOCK8 deficiency cases could not found in this study. CONCLUSION: The use of additional markers (CD45RA+, CD45RO+, CD27+IgD-) with BTK, LRBA, DOCK8 intracellular protein expression evaluation and DHR123 assay by flow-cytometry can increase rate of specific diagnosis of the PIDD cases in Bangladeshi paediatric population.