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K21-antigen: a molecule shared by the microenvironments of the human thymus and germinal centers

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Title: K21-antigen: a molecule shared by the microenvironments of the human thymus and germinal centers
Authors: Imami, N
Ladyman, HM
Vincents, B
Al-Tubuly, A
Freysdóttir, J
Sedibane, ML
Taylor-Fishwick, DA
Foxwell, BM
Ritter, MA
Item Type: Journal Article
Abstract: The mouse IgG1 monoclonal antibody (mAb) K21 recognizes a 230-kD molecule (K21-Ag) on Hassalls corpuscles in the human thymus. This mAb also stains cultured thymic epithelial cells as well as other epithelial cell lines, revealing a predominant intracellular localization. Further analysis with mAb K21 on other lymphoid tissues showed that it also stains cells within the germinal centers of human tonsils, both lymphoid (B) cells and some with the appearance of follicular dendritic cells. Double immunostaining of tonsil sections shows that K21-Ag is not expressed by T cells, whereas staining with anti-CD22 and -CD23 mAb revealed some double-positive cells. A subpopulation of the lymphoid cells express the K21-Ag much more strongly. This K21++/CD23++ subpopulation of cells is localized in the apical light zone of germinal centers, suggesting that K21-Ag may be an important marker for the selected centrocytes within germinal centers and may play a role in B-cell selection and/or development of B-cell memory. Flow cytometric analysis showed that K21-Ag is expressed on the surface of a very low percentage of thymocytes, tonsillar lymphocytes, and peripheral blood mononuclear cells. Analysis of purified/separated tonsillar T and B lymphocytes showed that T cells do not express the K21-Ag; in contrast, B cells express low levels of the K21-Ag, and this together with CD23 is upregulated after mitogenic stimulation. Our data therefore raise the possibility that the K21-Ag may play a role in B-lymphocyte activation/selection.
Issue Date: 31-Dec-1998
Date of Acceptance: 31-Dec-1998
URI: http://hdl.handle.net/10044/1/32987
DOI: http://dx.doi.org/10.1155/1998/29340
ISSN: 1044-6672
Start Page: 41
End Page: 52
Journal / Book Title: Developmental Immunology
Volume: 6
Issue: 1-2
Copyright Statement: © 1998 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Animals
Antibodies, Monoclonal
Cell Line
Flow Cytometry
Germinal Center
Receptors, Interleukin-4
Thymus Gland
1107 Immunology
Publication Status: Published
Appears in Collections:Department of Medicine (up to 2019)