title: Immunohistochemical characterization of lymphocytes in microscopic colitis.
abstract: OBJECTIVE
  Microscopic colitis (MC), encompassing the subgroups collagenous colitis (CC) and lymphocytic colitis (LC), is characterized by macroscopically normal or near-normal colonic mucosa, and an increased number of intraepithelial lymphocytes (IELs) and mononuclear cell infiltration in the underlying lamina propria (LP), in addition to an increased collagen layer in CC. This study aimed to characterize the inflammatory cells involved in mucosal inflammation, using immunohistochemistry.
  
  
  METHODS
  Paraffin-embedded biopsies from 23 untreated patients with MC (CC=13, LC=10) and 17 controls were stained with antibodies against CD3, CD4, CD8, CD20, CD30, Foxp3, CD45RO and Ki67. Computerized image analysis was used to calculate areas of stained lymphocytes in the surface and crypt epithelia as well as in the LP.
  
  
  RESULTS
  In CC and LC, an increase of predominantly CD8(+) lymphocytes was seen in both the epithelium and the lamina propria, whereas a decreased amount of CD4(+) lymphocytes was found in the lamina propria. CD45RO(+) and Foxp3(+) cells were more abundant in all areas in both patient groups compared to controls, as were CD20(+) areas, although more scarce. Ki67(+) areas were only more abundant in the epithelium, whereas CD30(+) areas were more abundant in the lamina propria of both patient groups compared to controls.
  
  
  CONCLUSIONS
  This study confirms an increased amount of CD8(+) lymphocytes in the epithelium. Lymphocytic proliferation and activation markers were more abundant, whereas a decreased amount of CD4(+) lymphocytes was seen in the LP. Further studies are needed to reveal the underlying mechanism(s).
authors.affiliation: Dept. of Medicine, Division of Gastroenterology, Örebro University Hospital, Sweden. Electronic address: carl.goranzon@orebroll.se.
authors.forename: C
authors.initials: C
authors.lastname: Göranzon
authors.forename: A K
authors.initials: AK
authors.lastname: Kumawat
authors.forename: E
authors.initials: E
authors.lastname: Hultgren-Hörnqvist
authors.forename: C
authors.initials: C
authors.lastname: Tysk
authors.forename: S
authors.initials: S
authors.lastname: Eriksson
authors.forename: J
authors.initials: J
authors.lastname: Bohr
authors.forename: N
authors.initials: N
authors.lastname: Nyhlin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000032:analysis*; D001402:B-Lymphocytes / Q000737:chemistry; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry; D046729:Colitis, Collagenous / Q000276:immunology* / Q000473:pathology; D046730:Colitis, Lymphocytic / Q000276:immunology* / Q000473:pathology; D005260:Female; D051858:Forkhead Transcription Factors / Q000032:analysis; D006801:Humans; D007413:Intestinal Mucosa / Q000276:immunology* / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis; D008214:Lymphocytes / Q000737:chemistry*; D008297:Male; D008875:Middle Aged
chemical_list: D015703:Antigens, CD; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D019394:Ki-67 Antigen
keywords: Collagenous colitis; Immunohistochemistry; Lymphocytes; Lymphocytic colitis; Microscopic colitis