title: Regional differences in L-selectin expression in murine intestinal lymphocytes.
abstract: OBJECTIVE
  The expression of the lymphocyte homing receptor and activation marker L-selectin is different in colon and small intestinal intraepithelial lymphocytes (IELs). In this study, the mechanism of this difference in L-selectin expression was investigated.
  
  
  METHODS
  L-selectin expression on lymphocytes was measured by flow cytometry. L-selectin messenger RNA (mRNA) was detected by reverse-transcription polymerase chain reaction. L-Selectin expression on peripheral lymphocytes was analyzed after incubation with cytokines, food and bacterial antigens, and homogenates of small and large bowel.
  
  
  RESULTS
  L-selectin was expressed by none of the small intestinal IELs but by 30% of those in the colon and by 60% of splenocytes. mRNA for L-selectin was detectable in isolated lymphocytes of all three sites. L-Selectin was down-regulated in colon IELs during colitis and up-regulated in small intestinal IELs after in vitro culture for 48 hours. Incubation of splenocytes with small intestinal homogenates led to a rapid down-regulation of L-selectin (1% vs. 60% untreated). Preincubation with a metalloproteinase inhibitor prevented L-selectin loss.
  
  
  CONCLUSIONS
  The mechanism of the differential expression of L-selectin in mouse small intestine and colon appears to be an increased functional activity of a metalloproteinase (sheddase) in the small intestine compared with the colon.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0007, USA.
authors.forename: F
authors.initials: F
authors.lastname: Seibold
authors.forename: B
authors.initials: B
authors.lastname: Seibold-Schmid
authors.forename: Y
authors.initials: Y
authors.lastname: Cong
authors.forename: F Y
authors.initials: FY
authors.lastname: Shu
authors.forename: R P
authors.initials: RP
authors.lastname: McCabe
authors.forename: C
authors.initials: C
authors.lastname: Weaver
authors.forename: C O
authors.initials: CO
authors.lastname: Elson
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D004847:Epithelial Cells / Q000166:cytology; D006877:Hydroxamic Acids / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D019041:L-Selectin / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D006877:Hydroxamic Acids; C112023:KD-IX 73-5; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D019041:L-Selectin; D008666:Metalloendopeptidases; D000409:Alanine