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Developmental Immunology
Volume 1, Issue 2, Pages 97-104

Expression of Class II Major Histocompatibility Complex Antigens on Adult T Cells in Xenopus is Metamorphosis- Dependent

Department of Pediatrics, Division of Pediatric Immunology and Rheumatology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA

Received 20 February 1990; Accepted 9 April 1990

Copyright © 1990 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.


Class II major histocompatibility complex (MHC) antigens are expressed predominantly on B lymphocytes and macrophages of tadpoles of the South African clawed frog, Xenopus laevis, as is the pattern in lymphocyte populations of most mammals. However, unlike most mammals, young postmetamorphic frogs show expression of class II MHC antigens on a high proportion of thymocytes and most peripheral T and B lymphocytes. Using the J-strain of Xenopus and the anticlass II monoclonal antibody, 14A2, we have studied, by indirect immunofluorescence, whether inhibition of metamorphosis would alter the pattern of expression of class II antigens during ontogeny. In control animals, class II antigens were virtually absent from thymic lymphocytes and peripheral T cells of normal untreated larvae, but could be found in increasing numbers in both populations after metamorphosis (10-12 weeks of age). In contrast, larvae, whose metamorphosis was inhibited by treatment with sodium perchlorate, had relatively few class II+ thymic lymphocytes throughout the 6-month period of study, and the proportion of class II+ splenic lymphocytes was approximately equal to that of IgM+ B lymphocytes. Thus, perchlorate-treated animals retained the larval pattern of class II epression, suggesting that emergence of class II+ T cells is dependent on metamorphosis.