title: CD4+ CD8+ and CD8alpha+ beta- T lymphocytes in human small intestinal lamina propria.
abstract: OBJECTIVE
  To examine CD8 expression by T-lymphocyte subpopulations from disease-free human lamina propria.
  
  
  METHODS
  Single-cell suspensions were prepared from the epithelial layer and the lamina propria of small intestinal biopsies obtained endoscopically from disease-free patients. Monoclonal antibodies against CD3, CD4, CD8, CD56, CD8alphabeta, CD8alpha, TCR alphabeta and TCR gammadelta were used for dual and three-colour flow cytometric analysis.
  
  
  RESULTS
  In addition to classical CD4+ and CD8+ T lymphocytes a substantial proportion of lamina propria T lymphocytes were CD4+ CD8+ or 'double positive' (mean 14%, range 4-26%). This population was significantly lower in the epithelial layer of the same patients (mean 7%, range 3-21%, P < 0.007). Three-colour flow cytometric analysis revealed that expression of the CD8 molecule on double positive T cells in the lamina propria was limited to the CD8alpha chain. Furthermore, of the CD8+ population, CD8+ T cells which only expressed the alpha chain were present in greater numbers in the lamina propria (mean 35%, range 14-54%) than in the epithelial layer (mean 18%, range 5-37%, P < 0.02). NK (CD56+) cells were not detected and few gammadeltaTCR+ T lymphocytes were detected in the lamina propria (mean 2%, range 0.5-6.6%) when compared with the epithelial layer (mean 8%, range 0.2-14%, P < 0.008).
  
  
  CONCLUSIONS
  A significant population of CD4+ CD8alpha+ T lymphocytes which are CD8beta chain negative have been detected in the intestinal lamina propria. These cells form a more significant component of the lamina propria than the epithelial layer T-cell repertoire and may have a unique function in intestinal immunoregulation.
authors.affiliation: Department of Immunology, St. James's Hospital, Dublin, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: Abuzakouk
authors.forename: J
authors.initials: J
authors.lastname: Carton
authors.forename: C
authors.initials: C
authors.lastname: Feighery
authors.forename: D P
authors.initials: DP
authors.lastname: O'Donoghue
authors.forename: D G
authors.initials: DG
authors.lastname: Weir
authors.forename: C
authors.initials: C
authors.lastname: O'Farrelly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015496:CD4-Positive T-Lymphocytes; D018414:CD8-Positive T-Lymphocytes; D004386:Duodenum / Q000276:immunology / Q000473:pathology*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D016176:T-Lymphocyte Subsets
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta