T-cell activation discriminates subclasses of symptomatic primary humoral immunodeficiency diseases in adults

Epigenetic immune cell quantification for diagnostic evaluation and monitoring of patients with inborn errors of immunity and secondary immune deficiencies

BACKGROUND

Early detection and monitoring of primary immunodeficiencies (PID) in humans require quantitative determination of immune cells from fresh blood analyzed by flow cytometry. However, epigenetic immune cell quantification allows analysis from fresh, frozen, or dried blood samples. We demonstrate the utility of epigenetic immune cell quantification for patients with PID.

METHODS

Epigenetic quantification of basic lymphocyte subpopulations of 259 samples from PID patients were compared to flow cytometric data. Epigenetic analysis was extended to T-cell subsets (Treg, Th17, Tfh, PD-1+, CCR6+) and memory B-cells and compared between venous EDTA and dried blood.

RESULTS

A high correlation of >0.9 was observed for basic T- and B-cell subsets. Extended epigenetic analysis showed quantitative trends within PID subgroups, but individually these varied substantially within these groups. Epigenetic analysis of dried blood samples was equivalent to EDTA blood.

CONCLUSION

Epigenetic immune cell quantification is suitable for immune cell profiling in PID patients.

STAT expression and TFH1 cells in CVID granulomatosis and sarcoidosis: immunological and histopathological comparisons

Granulomatous disease is a serious complication of common variable immunodeficiency (CVID-GD) that occurs in 8-22% of these patients and can mimic sarcoidosis, with which it shares certain clinical, biological, and radiological features. However, few studies to date have compared the two pathologies immunologically and histologically. Therefore, we analyzed the immunological-histological findings for different tissue samples from ten patients with CVID-GD and compared them to those of biopsy-proven sarcoidosis. Specifically, we wanted to know whether or not the signaling abnormalities observed in sarcoidosis granulomas are also present in CVID-GD. Morphological differences were found between CVID-GD histology and classical sarcoidosis: mainly, the former's notable lymphoid hyperplasia associated with granulomas not observed in the latter. All CVID-GD involved organs contained several follicular helper-T (TFH) cells within the granulomatosis, while those cells were inconstantly and more weakly expressed in sarcoidosis. Moreover, CVID and sarcoidosis granulomas expressed the phosphorylated-signal transducer and activator of transcription (pSTAT)1 and pSTAT3 factors, regardless of the organ studied and without any significant difference between entities. Our results suggest that the macrophage-activation mechanism in CVID resembles that of sarcoidosis, thereby suggesting that Janus kinase (JAK)-STAT-pathway blockade might be useful in currently difficult-to-treat CVID-GD.

Assessment of circulating blood lymphocytes in adult patients on rituximab to treat immune thrombocytopenia: Circulating number of NK cells is associated with the response at 6 months

Immune thrombocytopenia (ITP) is defined by a low platelet count that can trigger potentially life-threatening haemorrhages. Three-quarters of adult patients exhibit persistent or chronic disease and require second-line treatments. Among these, rituximab, an anti-CD20 antibody, has yielded valuable results, with global responses in 60% of patients at 6 months and complete responses in 30% at 5 years. Factors predictive of response to ITP therapy would help physicians choose optimal treatments. We retrospectively analysed clinical courses, biological markers and blood lymphocyte subset numbers of 72 patients on rituximab to treat persistent/chronic ITP followed-up in our department between 2007 and 2021, divided into three groups according to the platelet count at 6 months: complete, partial or no response. Among all studied parameters, a low number of CD3^- CD16⁺ CD56⁺ circulating NK cells was associated with the complete response to rituximab. We also found that, after rituximab therapy, complete responders exhibited increased NK and decreased activated CD8⁺ T cell percentages. These results emphasize that the role played by NK cells in ITP remains incompletely known but that factors predictive of response to rituximab can be easily derived using blood lymphocyte subset data.

Protocol for the unclassified primary antibody deficiency (unPAD) study: Characterization and classification of patients using the ESID online Registry

Background

Primary antibody deficiencies (PADs) without an identified monogenetic origin form the largest and most heterogeneous group of primary immunodeficiencies. These patients often remain undiagnosed for years and many present to medical attention in adulthood after several infections risking structural complications. Not much is known about their treatment, comorbidities, or prognosis, nor whether the various immunological forms (decreased total IgG, IgG subclass(es), IgM, IgA, specific antibody responses, alone or in combination(s)) should be considered as separate, clearly definable subgroups. The unclassified primary antibody deficiency (unPAD) study aims to describe in detail all PAD patients without an identified specific monogenetic defect regarding their demographical, clinical, and immunological characteristics at presentation and during follow-up. In constructing these patterns, the unPAD study aims to reduce the number of missed and unidentified PAD patients in the future. In addition, this study will focus on subclassifying unPAD to support the identification of patients at higher risk for infection or immune dysregulation related complications, enabling the development of personalized follow-up and treatment plans.

Methods and analysis

We present a protocol for a multicenter observational cohort study using the ESID online Registry. Patients of all ages who have given informed consent for participation in the ESID online Registry and fulfill the ESID Clinical Working Definitions for ‘unclassified antibody deficiency’, ‘deficiency of specific IgG’, ‘IgA with IgG subclass deficiency’, ‘isolated IgG subclass deficiency’, ‘selective IgM deficiency’, ‘selective IgA deficiency’ or ‘common variable immunodeficiency’ will be included. For all patients, basic characteristics can be registered at first registration and yearly thereafter in level 1 forms. Detailed characteristics of the patients can be registered in level 2 forms. Consecutive follow-up forms can be added indefinitely. To ensure the quality of the collected data, all data will be fully monitored before they are exported from the ESID online Registry for analysis. Outcomes will be the clinical and immunological characteristics of unPAD at presentation and during follow-up. Subgroup analyses will be made based on demographical, clinical and immunological characteristics.

The immunophenotypic fingerprint of patients with primary antibody deficiencies is partially present in their asymptomatic first-degree relatives

The etiology of primary antibody deficiencies is largely unknown. Beside rare monogenic forms, the majority of cases seem to have a more complex genetic basis. Whereas common variable immunodeficiency has been investigated in depth, there are only a few reports on milder primary antibody deficiencies such as idiopathic primary hypogammaglobulinemia and IgG subclass deficiency. We performed flow cytometric immunophenotyping in 33 patients with common variable immunodeficiency, 23 with idiopathic primary hypogammaglobulinemia and 21 with IgG subclass deficiency, as well as in 47 asymptomatic first-degree family members of patients and 101 unrelated healthy controls. All three groups of patients showed decreased memory B- and naïve T-cell subsets and decreased B-cell activating factor receptor expression. In contrast, circulating follicular helper T-cell frequency and expression of inducible T-cell co-stimulator and chemokine receptors were only significantly altered in patients with common variable immunodeficiency. Asymptomatic first-degree family members of patients demonstrated similar, albeit intermediate, alterations in naïve and memory B- and T-cell subsets. About 13% of asymptomatic relatives had an abnormal peripheral B-cell composition. Furthermore, asymptomatic relatives showed decreased levels of CD4⁺ recent thymic emigrants and increased central memory T cells. Serum IgG and IgM levels were also significantly lower in asymptomatic relatives than in healthy controls. We conclude that, in our cohort, the immunophenotypic landscape of primary antibody deficiencies comprises a spectrum, in which some alterations are shared between all primary antibody deficiencies whereas others are only associated with common variable immunodeficiency. Importantly, asymptomatic first-degree family members of patients were found to have an intermediate phenotype for peripheral B- and T-cell subsets.