Expression of class II major histocompatibility complex antigens on adult T cells in Xenopus is metamorphosis-dependent.
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 expression, suggesting that emergence of class II+ T cells is dependent on metamorphosis.
Rollins-Smith
L A
LA
Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Blair
P
P
D000818:Animals; D002452:Cell Count; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D007814:Larva / Q000187:drug effects / Q000276:immunology; D008675:Metamorphosis, Biological / Q000187:drug effects / Q000276:immunology; D008856:Microscopy, Fluorescence; D010472:Perchlorates / Q000494:pharmacology; D017670:Sodium Compounds; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology; D014982:Xenopus laevis / Q000254:growth & development* / Q000276:immunology*
D000949:Histocompatibility Antigens Class II; D010472:Perchlorates; D017670:Sodium Compounds; C031068:sodium perchlorate