title: Lymphocytosis of gamma/delta T cells in human ehrlichiosis.
abstract: The majority of T cells in peripheral blood express a T-cell receptor (TCR) comprised of alpha and beta chains. An alternate form of the TCR is comprised of gamma and delta chains. These gamma/delta T cells are associated with certain infectious lesions, and modestly elevated in peripheral blood in certain disease states. Human ehrlichiosis is characterized by hematologic abnormalities including multi-lineage cytopenias. In most cases reported, a lymphocytopenia has been present either at diagnosis, or at some time during the illness. Early in the course of antibiotic treatment (48-72 hours), the lymphocytopenia corrects itself and is rapidly followed by a lymphocytosis of T cells that express CD3, but are negative for CD4 and CD8, as well as the major form of the TCR formed by the alpha/beta heterodimer. Instead, these CD3+4-8- T cells express the gamma/delta heterodimer associated with V gamma 9 and V delta 2 chains, a population of cells usually the distinctive minority of peripheral blood T cells, but constituting the major phenotype of peripheral gamma/delta T cells.
authors.affiliation: Department of Pathology and Anatomic Sciences, University of Missouri School of Medicine, Columbia, 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
mesh_terms: D016873:Ehrlichiosis / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D016130:Immunophenotyping; D018655:Lymphocyte Count; D008218:Lymphocytosis / Q000378:metabolism* / Q000473:pathology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology*; D013997:Time Factors
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta