Pathology, immunohistology, and cytokine responses in early phases of human granulocytic ehrlichiosis in a murine model

Mary E. Martin, Joseph E. Bunnell, J. Stephen Dumler

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Human granulocytic ehrlichiosis (HGE) results in fever, pancytopenia, and mild liver injury. We used a mouse model to examine immunity in the pathogenesis of HGE. HGE agent-infected C3H/HeJ mice were necropsied over 21 days. Histologic, immunohistologic, and serologic analyses, blood culture, tissue and blood polymerase chain reaction (PCR), cell counts, serum chemistries, and plasma cytokine ELISAs were performed. No clinical signs were detected. Ehrlichiae were identified in neutrophils in hematopoietic tissues maximally on day 7. Interleukin (IL)-10 levels were high throughout, whereas interferon (IFN)-γ levels peaked on days 7 and 10 and dropped thereafter. Hepatic lymphohistiocytic aggregates with apoptoses were maximal at day 14. HGE-agent infection of mice induces pathologic changes similar to those in infected humans, despite differences in cytokine profile. The IFN-γ peak prior to maximal pathologic change, when ehrlichiae are absent in tissues, suggests a role for host immunity in the pathogenesis of HGE.

Original languageEnglish (US)
Pages (from-to)374-378
Number of pages5
JournalJournal of Infectious Diseases
Issue number1
StatePublished - Jan 26 2000


ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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