Skip to content

Advertisement

Volume 3 Supplement 1

ESICM LIVES 2015

  • Poster presentation
  • Open Access

Activation-associated death of memory b cells in peripheral circulation in adults with sepsis

  • 1, 2,
  • 2,
  • 3, 4 and
  • 1
Intensive Care Medicine Experimental20153 (Suppl 1) :A621

https://doi.org/10.1186/2197-425X-3-S1-A621

  • Published:

Keywords

  • Lymphocyte Count
  • Secondary Lymphoid Organ
  • Grant Acknowledgment
  • Annexin Versus Apoptosis Detection
  • Population Gate

Introduction

In sepsis, impaired function and loss of antigen-presenting cells are observed in secondary lymphoid organs [1], the site where antigen-dependent B cell differentiation occurs in health. How these changes in sepsis affect B cell differentiation into memory B cells is at present undefined.

Objectives

To study seven-day lymphocyte and immunoglobulin trajectory, alterations in B cell subsets and potential mechanisms in septic ICU patients.

Methods

Adults with severe sepsis from community-acquired infections without documented immunosuppression were enrolled. Hypogammaglobulinaemia and absolute lymphopenia were defined as IgG < 6.1, IgM < 0.4, IgA < 0.8 g/L and lymphocytes < 1.2 × 109/L, respectively.

Flow cytometry [FACScalibur [BD Biosciences]; FlowJo software,] was used for:

Identifying naïve, transitional, IgM, IgG and IgA memory and plasmablasts using anti-human CD19-PerCpCy5.5, IgG-APC H7, IgM-V450, CD24-PeCy7 [all BD Biosciences], IgA-FITC, CD38-PE, Annexin V Apoptosis detection set PE-Cy7 [all eBioscience] and live-dead stain [Invitrogen]. ADDIN EN.CITE ADDIN EN.CITE.DATA [2], [3]

Intracellular staining to assess phosphorylated kinase expression in B cells [p-ERK-PE, p-BTK-alexafluor 647, p-SYK-alexafluor 488, p-AKT-APC [all BD Biosciences].

FMO and isotype controls were used to define population gates.

B cell survival ligands [BAFF, APRIL] were measured using ELISA.

Differentially expressed genes in sepsis are reported [RT-q-PCR, TaqMan® Human Apoptosis Array; false discovery rate = 5%].

Statistics were performed using paired and unpaired t test or non-parametric equivalent with adjustment for collinear measurements.

Results

101 patients were studied. On their first ICU day, 46% had hypogammaglobulinaemia and 76% absolute lymphopenia with absolute low B [75%] and T [100%] lymphocyte counts. Trajectory of significantly higher increment immunoglobulins and lymphocyte counts occur earlier in survivors compared to non-survivors.

In sepsis [compared to healthy controls, n=variable] there was

Preferential apoptotic loss of memory B cells and plasmablasts, with apoptotic cells showing higher phosphorylated extracellular signal-regulated kinases [p-ERK fluorescence], but no differences in the phosphorylated B cell receptor linked kinases [p-BTK, p-SYK] and protein kinase B.

BAFF/APRIL levels were normal.

Fas and bcl-2 apoptosis regulator genes were up regulated.

Conclusions

In sepsis, activation-associated B cell apoptosis and changes in secondary lymphoid organs deplete B cell memory and contribute to long-term immunosuppression in survivors.

Grant Acknowledgment

UK NIHR, Biomedical Research Centre at Guy´s and St Thomas´ NHS Trust & King´s College London

Authors’ Affiliations

(1)
Department of Immunobiology, King's College London, London, United Kingdom
(2)
Guy's and St Thomas' NHS Foundation Trust, Critical Care Medicine, London, United Kingdom
(3)
University College London, Intensive Care Medicine, London, United Kingdom
(4)
Research Department of Clinical Physiology, Division of Medicine, University College London, London, United Kingdom

References

  1. Hotchkiss RS, et al: Nat Rev Immunol. 2013, 13: 862-874. 10.1038/nri3552.PubMedPubMed CentralView ArticleGoogle Scholar
  2. Maecker H, et al: Nat Rev Immunol. 2012, 12: 191-200.PubMedPubMed CentralGoogle Scholar
  3. Berkowska MA, et al: Blood. 2011, 118: 2150-2158. 10.1182/blood-2011-04-345579.PubMedPubMed CentralView ArticleGoogle Scholar

Copyright

© Shankar-Hari et al.; 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Advertisement