Email updates

Keep up to date with the latest news and content from BMC Immunology and BioMed Central.

Open Access Research article

Immune Mediators of protective and pathogenic immune responses in patients with mild and fatal human monocytotropic ehrlichiosis

Nahed Ismail135*, David H Walker2, Purnima Ghose3 and Yi-Wei Tang4

Author Affiliations

1 Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA

2 Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA

3 Department of Pathology, Meharry Medical College, Nashville, TN, USA

4 Departments of Pathology and Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, USA

5 Department of Pathology, University of Pittsburgh, S739 Scaife Hall, 3550 Terrace St, 15261, Pittsburgh, PA, USA

For all author emails, please log on.

BMC Immunology 2012, 13:26  doi:10.1186/1471-2172-13-26

Published: 21 May 2012

Abstract

Background

Ehrlichia chaffeensis is a bacterial pathogen that causes fatal human monocytic ehrlichiosis (HME) that mimic toxic shock-like syndrome. Murine studies indicate that over activation of cellular immunity followed by immune suppression plays a central role in mediating tissue injury and organ failure during fatal HME. However, there are no human studies that examine the correlates of resistance or susceptibility to severe and fatal HME.

Results

In this study, we compared the immune responses in two patients with mild/non fatal and severe/fatal HME who had marked lymphopenia, thrombocytopenia and elevated liver enzymes. The levels of different immunological factors in the blood of those patients were examined and compared to healthy controls. Our data showed that fatal HME is associated with defective production of Th1 cytokines such as ( IFNγ and IL-2), increased anti-inflammatory (IL-10 and IL-13) and pro-inflammatory (TNF-α, IL-1α, IL-1β, and IL-6) cytokines, increased levels of macrophages, T cells, and NK cells chemokines such as MCP-1, MIP-1α, MIP-1β, but not RANTES and IP-10, increased levels of neutrophils chemokine and growth factor (IL-8 and G-CSF), and elevated expression of tumor necrosis factor receptor (TNFR), and toll like receptors 2 and 4 compared to patients with non fatal HME and healthy controls.

Conclusions

Fatal Ehrlichia-induced toxic shock is associated with defective Th1 responses, possible immune suppression mediated by IL-10. In addition, marked leukopenia observed in patients with fatal disease could be attributed to enhanced apoptosis of leukocytes and/or elevated chemokine production that could promote migration of immune cells to sites of infection causing tissue injury.

Keywords:
Human ehrlichiosis; Toxic shock; T cells; Cytokines; Chemokines; Apoptosis; Ehrlichiosis; Pro-inflammatory cytokines; Death Receptors; Th1 response