title: Comparative immunophenotypic features of EBV-positive and EBV-negative atypical lymphocytosis.
abstract: BACKGROUND
  Atypical lymphocytosis is a common peripheral blood abnormality seen not only in Epstein-Barr virus (EBV)-associated acute infectious mononucleosis but also in other conditions, including other viral infections, cancer, immune reactions, etc. Despite numerous reports of individual immunophenotypic alterations in EBV-positive infectious mononucleosis, a detailed comparative analysis of the immunophenotypic changes of peripheral blood lymphocyte subsets in infectious mononucleosis and other forms of atypical lymphocytosis is lacking.
  
  
  METHODS
  Multiparametric flow immunocytometry with 26 monoclonal antibodies was performed on peripheral blood lymphocytes from 97 cases of atypical lymphocytosis and 37 normal controls. Atypical lymphocytosis was defined as absolute lymphocytosis with >10% atypical lymphocytes. Absolute or relative mean values of various lymphocyte subsets from EBV-positive cases, EBV-negative cases, and normal controls were compared with the Student's t-test.
  
  
  RESULTS
  Highly significant abnormalities detected in atypical lymphocytosis include increases in CD3+/CD8+, CD3-/CD16/56+, CD3+/gammadelta+, CD8+/CD48-, CD8+/CD57-, CD8+/CD95+, CD4+/CCR5+ CD4+/CD7-, CD4+/CD43-, CD4+/CD48-, and CD4+/CD62L- subsets. In contrast, no change in absolute CD4+ T cell and CD19+ B cell counts is seen. When compared with EBV-negative cases, EBV-positive cases are characterized by younger age, and increased numbers of absolute lymphocytes, atypical lymphocytes, CD8+ cells, NK cells, gammadelta T cells, CD8+/CD45RO+ cells, CD8+/CD57- cells, and CD8+/CD28+ cells.
  
  
  CONCLUSIONS
  All forms of atypical lymphocytosis are characterized by a marked increase in activated CD8-positive T cells, a moderate increase in NK cells, and no increase in CD4-positive T cells and B cells. Although morphologically indistinguishable, EBV-associated mononucleosis is characterized by several significant differences in peripheral blood lymphocyte subsets when compared with EBV-negative atypical lymphocytosis, most notably increased numbers of CD57-negative CD8 T cells and gammadelta T cells.
authors.affiliation: Hematopathology Division, Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555, USA. shudnall@utmb.edu
authors.forename: S David
authors.initials: SD
authors.lastname: Hudnall
authors.forename: Jyoti
authors.initials: J
authors.lastname: Patel
authors.forename: Hanna
authors.initials: H
authors.lastname: Schwab
authors.forename: José
authors.initials: J
authors.lastname: Martinez
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000821:virology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D005434:Flow Cytometry; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D016130:Immunophenotyping; D007244:Infectious Mononucleosis / Q000276:immunology* / Q000821:virology; D007694:Killer Cells, Natural / Q000276:immunology / Q000821:virology; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology* / Q000821:virology; D008218:Lymphocytosis / Q000276:immunology* / Q000821:virology
chemical_list: D015703:Antigens, CD