INTRODUCTION: Common Variable Immunodeficiency (CVID) is characterized by defective antibody production and hypogammaglobulinemia. Flow cytometry immunophenotyping of blood lymphocytes has become of great relevance for the diagnosis and classification of CVID, due to an impaired differentiation of mature post-germinal-center (GC) class-switched memory B-cells (MBC) and severely decreased plasmablast/plasma cell (Pb) counts. Here, we investigated in detail the pre-GC B-cell maturation compartment in blood of CVID patients. METHODS: In this collaborative multicentric study the EuroFlow PID 8-color Pre-GC B-cell tube, standardized sample preparation procedures (SOPs) and innovative data analysis tools, were used to characterize the maturation profile of pre-GC B-cells in 100 CVID patients, vs 62 age-matched healthy donors (HD). RESULTS: The Pre-GC B-cell tube allowed identification within pre-GC B-cells of three subsets of maturation associated immature B-cells and three subpopulations of mature naïve B-lymphocytes. CVID patients showed overall reduced median absolute counts (vs HD) of the two more advanced stages of maturation of both CD5+ CD38+/++ CD21het CD24++ (2.7 vs 5.6 cells/µl, p=0.0004) and CD5+ CD38het CD21+ CD24+ (6.5 vs 17 cells/µl, p<0.0001) immature B cells (below normal HD levels in 22% and 37% of CVID patients). This was associated with an expansion of CD21-CD24- (6.1 vs 0.74 cells/µl, p<0.0001) and CD21-CD24++ (1.8 vs 0.4 cells/µl, p<0.0001) naïve B-cell counts above normal values in 73% and 94% cases, respectively. Additionally, reduced IgMD+ (21 vs 32 cells/µl, p=0.03) and IgMD- (4 vs 35 cells/µl, p<0.0001) MBC counts were found to be below normal values in 25% and 77% of CVID patients, respectively, always together with severely reduced/undetectable circulating blood pb. Comparison of the maturation pathway profile of pre-GC B cells in blood of CVID patients vs HD using EuroFlow software tools showed systematically altered patterns in CVID. These consisted of: i) a normally-appearing maturation pathway with altered levels of expression of >1 (CD38, CD5, CD19, CD21, CD24, and/or smIgM) phenotypic marker (57/88 patients; 65%) for a total of 3 distinct CVID patient profiles (group 1: 42/88 patients, 48%; group 2: 8/88, 9%; and group 3: 7/88, 8%) and ii) CVID patients with a clearly altered pre-GC B cell maturation pathway in blood (group 4: 31/88 cases, 35%). CONCLUSION: Our results show that maturation of pre-GC B-cells in blood of CVID is systematically altered with up to four distinctly altered maturation profiles. Further studies, are necessary to better understand the impact of such alterations on the post-GC defects and the clinical heterogeneity of CVID.

• Klíčová slova
• CVID, EuroFlow standardization, Pre-GC B-cell tube, expression markers, pre-GC maturation pathway,
• MeSH
• běžná variabilní imunodeficience diagnóza   imunologie   metabolismus   MeSH
• CD antigeny analýza   MeSH
• dospělí MeSH
• fenotyp MeSH
• imunofenotypizace * MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• prekurzorové B-lymfoidní buňky imunologie   metabolismus   MeSH
• průtoková cytometrie * MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• studie případů a kontrol MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Názvy látek
• CD antigeny MeSH

Common variable immunodeficiency (CVID) is a heterogeneous group of diseases. Our aim was to define sub-groups of CVID patients with similar phenotypes and clinical characteristics. Using eight-color flow cytometry, we analyzed both B- and T-cell phenotypes in a cohort of 88 CVID patients and 48 healthy donors. A hierarchical clustering of probability binning "bins" yielded a separate cluster of 22 CVID patients with an abnormal phenotype. We showed coordinated proportional changes in naïve CD4+ T-cells (decreased), intermediate CD27- CD28+ CD4+ T-cells (increased) and CD21low B-cells (increased) that were stable for over three years. Moreover, the lymphocytes' immunophenotype in this patient cluster exhibited features of profound immunosenescence and chronic activation. Thrombocytopenia was only found in this cluster (36% of cases, manifested as Immune Thrombocytopenia (ITP) or Evans syndrome). Clinical complications more frequently found in these patients include lung fibrosis (in 59% of cases) and bronchiectasis (55%). The degree of severity of these symptoms corresponded to more deviation from normal levels with respect to CD21low B-cells, naïve CD4+ and CD27− CD28+ CD4+ T-cells. Next-generation sequencing did not reveal any common genetic background. We delineate a subgroup of CVID patients with activated and immunosenescent immunophenotype of lymphocytes and distinct set of clinical complications without common genetic background.

• MeSH
• aktivace lymfocytů MeSH
• B-lymfocyty imunologie   MeSH
• běžná variabilní imunodeficience imunologie   MeSH
• CD4-pozitivní T-lymfocyty imunologie   MeSH
• dospělí MeSH
• fenotyp MeSH
• fibróza MeSH
• idiopatická trombocytopenická purpura imunologie   MeSH
• imunosenescence MeSH
• kohortové studie MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• plíce patologie   MeSH
• průtoková cytometrie MeSH
• senioři MeSH
• separace buněk MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH