Naïve Regulatory T Cell Subset Is Altered in X-Linked Agammaglobulinemia

Severe Tick-Borne Encephalitis (TBE) in a Patient with X-Linked Agammaglobulinemia; Treatment with TBE Virus IgG Positive Plasma, Clinical Outcome and T Cell Responses

PURPOSE

A patient with X-linked agammaglobulinemia (XLA) and severe tick-borne encephalitis (TBE) was treated with TBE virus (TBEV) IgG positive plasma. The patient's clinical response, humoral and cellular immune responses were characterized pre- and post-infection.

METHODS

ELISA and neutralisation assays were performed on sera and TBEV PCR assay on sera and cerebrospinal fluid. T cell assays were conducted on peripheral blood the patient and five healthy vaccinated controls.

RESULTS

The patient was admitted to the hospital with headache and fever. He was not vaccinated against TBE but receiving subcutaneous IgG-replacement therapy (IGRT). TBEV IgG antibodies were low-level positive (due to scIGRT), but the TBEV IgM and TBEV neutralisation tests were negative. During hospitalisation his clinical condition deteriorated (Glasgow coma scale 3/15) and he was treated in the ICU with corticosteroids and external ventricular drainage. He was then treated with plasma containing TBEV IgG without apparent side effects. His symptoms improved within a few days and the TBEV neutralisation test converted to positive. Robust CD8+ T cell responses were observed at three and 18-months post-infection, in the absence of B cells. This was confirmed by tetramers specific for TBEV.

CONCLUSION

TBEV IgG-positive plasma given to an XLA patient with TBE without evident adverse reactions may have contributed to a positive clinical outcome. Similar approaches could offer a promising foundation for researching therapeutic options for patients with humoral immunodeficiencies. Importantly, a robust CD8+ T cell response was observed after infection despite the lack of B cells and indicates that these patients can clear acute viral infections and could benefit from future vaccination programs.

T Cell Abnormalities in X-Linked Agammaglobulinaemia: an Updated Review

X-linked agammaglobulinaemia (XLA) is a primary immunodeficiency (PID) resulting from a defect in the B cell development. It has conventionally been thought that T cells play a major role in the development and function of the B cell compartment. However, it has also been shown that B cells and T cells undergo bidirectional interactions and B cells also influence the structure and function of the T cell compartment. Patients with XLA offer a unique opportunity to understand the effect of absent B cells on the T cell compartment. In this review, we provide an update on abnormalities in the T cell compartment in patients with XLA. Studies have shown impaired memory T cells, follicular helper T cells, T regulatory cells and T helper 17 in patients with XLA. In addition, these patients have also been reported to have abnormal delayed cell-mediated immune responses and vaccine-specific T cell-mediated immune responses; defective T helper cell polarization and impaired T cell receptor diversity. At present, the clinical significance of these T cell abnormalities has not been studied in detail. However, these abnormalities may result in an increased risk of viral infections, autoimmunity, autoinflammation and possibly chronic lung disease. Abnormal response to SARS-Cov2 vaccine in patients with XLA and prolonged persistence of SARS-Cov2 virus in the respiratory tract of these patients may be related to abnormalities in the T cell compartment.

Single-cell transcriptomic landscape identifies the expansion of peripheral blood monocytes as an indicator of HIV-1-TB co-infection

Certain circulating cell subsets are involved in immune dysregulation in human immunodeficiency virus type 1 (HIV-1) and tuberculosis (TB) co-infection; however, the characteristics and role of these subclusters are unknown. Peripheral blood mononuclear cells (PBMCs) of patients with HIV-1 infection alone (HIV-pre) and those with HIV-1-TB co-infection without anti-TB treatment (HIV-pre & TB-pre) and with anti-TB treatment for 2 weeks (HIV-pre & TB-pos) were subjected to single-cell RNA sequencing (scRNA-seq) to characterize the transcriptome of different immune cell subclusters. We obtained > 60,000 cells and identified 32 cell subclusters based on gene expression. The proportion of immune-cell subclusters was altered in HIV-1-TB co-infected individuals compared with that in HIV-pre-group, indicating immune dysregulation corresponding to different disease states. The proportion of an inflammatory CD14+CD16+ monocyte subset was higher in the HIV-pre & TB-pre group than in the HIV-pre group; this was validated in an additional cohort (n = 80) via a blood cell differential test, which also demonstrated a good discriminative performance (area under the curve, 0.8046). These findings depicted the atlas of immune PBMC subclusters in HIV-1-TB co-infection and demonstrate that monocyte subsets in peripheral blood might serve as a discriminating biomarker for diagnosis of HIV-1-TB co-infection.