title: Adult onset of T-cell deficiency with impaired CD2 expression complicated by Rhodococcus infection: a case report.
abstract: BACKGROUND
  The functional importance of CD2 in vivo is currently the subject of discussion.
  
  
  OBJECTIVE
  To describe a 47-year-old white man with systemic Rhodococcus infection, a rarely observed opportunistic disease, secondary to severe lymphopenia.
  
  
  METHODS
  We extensively characterized lymphocyte phenotype and function.
  
  
  RESULTS
  Both CD4+ and CD8+ T cells were severely diminished, with a particular reduction in alpha:beta T cells. Human immunodeficiency virus infection was excluded. CD2 expression was decreased not only on T cells but also on nonaffected natural killer cells. Production of interferon-gamma interleukin 2, and tumor necrosis factor a was normal. Neither B-cell numbers nor humoral immune responses were affected. In addition, adhesion molecules CD11a, CD54, and CD154 were normally expressed, as were the costimulatory molecules CD28, CD80, and CD86.
  
  
  CONCLUSIONS
  We hypothesize that prolonged disturbance of CD2 expression led to an acquired severe cellular immunodeficiency. This underlines the importance of CD2 in vivo, where it may play a role in the fine regulation of T-cell proliferation.
authors: Department of Clinical Immunology, Hannover Medical School, Hannover, Germany. jenskittner@yahoo.de
authors: Jens Martin
authors: JM
authors: Kittner
authors: Roland
authors: R
authors: Jacobs
authors: Sabine
authors: S
authors: Buyny
authors: Dietrich
authors: D
authors: Peest
authors: Matthias
authors: M
authors: Stoll
authors: Reinhold Ernst
authors: RE
authors: Schmidt
mesh_terms: D000193:Actinomycetales Infections / Q000150:complications / Q000276:immunology*; D018801:CD2 Antigens / Q000096:biosynthesis; D002478:Cells, Cultured; D006801:Humans; D008231:Lymphopenia / Q000209:etiology / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012240:Rhodococcus / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000473:pathology*
chemical_list: D018801:CD2 Antigens