title: Apoptosis of gamma/delta T cells in human ehrlichiosis.
abstract: Expansion of activated T cells expressing the T-cell receptor (TCR) gamma/delta, CD45RO, and HLA-DR antigens is a prominent feature of acute infection with Ehrlichia chaffeensis in humans. The fate of these activated cells and the resolution of the gamma/delta T-cell response with return to the usual alpha/beta T-cell populations in this disease are not clearly understood. At a morphologic level, apoptotic cells are present in the peripheral blood during the acute and resolution phases of the infection. Simple culture of density gradient-separated lymphocytes from the blood of patients with acute ehrlichiosis produced cell death rapidly in the media compared to alpha/beta T cells. This loss of viability after incubation was apparently mediated by apoptosis, based on flow cytometric and morphologic analyses. The results suggest that most primed (CD45RO+) and activated (HLA-DR+) gamma/delta T cells in acute ehrlichiosis might be subject to removal from the body by programmed or apoptotic cell death.
authors.affiliation: Department of Pathology and Anatomic Sciences, University of Missouri School of Medicine, Columbia 65203, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Caldwell
authors.forename: E D
authors.initials: ED
authors.lastname: Everett
authors.forename: G
authors.initials: G
authors.lastname: McDonald
authors.forename: Y W
authors.initials: YW
authors.lastname: Yesus
authors.forename: W E
authors.initials: WE
authors.lastname: Roland
authors.forename: H M
authors.initials: HM
authors.lastname: Huang
mesh_terms: D017209:Apoptosis; D002470:Cell Survival; D002478:Cells, Cultured; D018469:Ehrlichia chaffeensis; D016873:Ehrlichiosis / Q000473:pathology*; D005434:Flow Cytometry; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear; D008214:Lymphocytes / Q000473:pathology; D016692:Receptors, Antigen, T-Cell, gamma-delta; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology*
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta; D017493:Leukocyte Common Antigens