title: The role of CD5 expression in thymic carcinoma: possible mechanism for interaction with CD5+ lymphoid stroma (microenvironment).
abstract: OBJECTIVE
  Most thymic carcinomas express the lymphocyte marker CD5 aberrantly. This study was performed to examine the role of the self-reactive CD5 antigen in thymic carcinoma.
  
  
  RESULTS
  We examined CD5 expression in thymic carcinoma in relation to the lymphoid stroma. All cases of thymic carcinoma examined expressed CD5. A number of CD5(+) lymphocytes were also present in the stroma of thymic carcinoma. The CD5(+) tumour areas were predominantly in contact with the lymphoid stroma, and the expression level was significantly lower in tumour cells than lymphocytes. Although p53 and Bcl-2 expression levels were significantly higher in thymic carcinoma than normal thymic epithelial cells (TECs), they did not differ between CD5(+) and CD5(-) areas. E-cadherin expression in thymic carcinoma was comparable with that of normal TECs, and it also did not differ between these areas. In contrast, both Ki-67 index and mitotic activity were significantly higher in thymic carcinoma than normal TECs, and they were significantly higher in CD5(+) than CD5(-) areas.
  
  
  CONCLUSIONS
  CD5 may be induced by interaction with CD5(+) lymphoid stroma, and may be related to tumour proliferation. CD5 induction may also be a significant and/or specific effect of the tumour microenvironment of the thymus.
authors.affiliation: Department of Pathology, Kori Hospital-Kansai Medical University, Osaka, Japan.|Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Osaka, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hosaka
authors.affiliation: Department of Diagnostic Pathology, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Ohe
authors.affiliation: Department of Diagnostic Pathology, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Miyasaka
authors.affiliation: Department of Diagnostic Pathology, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Yorika
authors.initials: Y
authors.lastname: Nakano
authors.affiliation: Department of Diagnostic Pathology, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Sakaida
authors.affiliation: Department of Diagnostic Pathology, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Uemura
authors.affiliation: Division of Thoracic Surgery, Hirakata Hospital-Kansai Medical University, Osaka, Japan.
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Department of Stem Cell Disorders, Kansai Medical University, Osaka, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Ikehara
authors.affiliation: Department of Pathology II, Kansai Medical University, Osaka, Japan.
authors.forename: Airo
authors.initials: A
authors.lastname: Tsubura
authors.affiliation: Department of Clinical Sciences and Laboratory Medicine, Kansai Medical University, Osaka, Japan.
authors.forename: Hakuo
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D018956:CD5 Antigens / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism / Q000473:pathology; D013945:Thymoma / Q000378:metabolism* / Q000473:pathology; D013953:Thymus Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D018956:CD5 Antigens; D015820:Cadherins
keywords: CD5; thymic carcinoma