The proliferative in vivo activities of lpr double-negative T cells and the primary role of p59fyn in their activation and expansion.
To characterize the functional status of lpr T cells and determine whether activation is required for DN cell expansion, we performed in vivo labeling experiments in MRL-+/+, MRL-lpr, and p59fyn-/- MRL-lpr (Fyn-/-) mice. Multicolor FACS analysis of T cells from 8-wk-old mice receiving bromodeoxyuridine (BrdUrd) for 9 days showed that higher proportions of CD4+ and CD8+ lymph node cells were dividing (BrdUrd(high)) in lpr (15%) than in +/+ mice (3%), and the proportion of cycling cells was even higher in the DN (71%) and CD4+ B220+ (54%) lpr subsets. BrdUrd chase experiments documented that activation and division in most DN cells was initiated subsequent to their precursor CD8+ stage. Lymphadenopathy and other disease manifestations were greatly reduced in Fyn-/- lpr mice concomitant to decreased DN cells (from 77 to 20%). BrdUrd chase experiments showed that the division rate, signified by conversion of DN cells from BrdUrd(high) to BrdUrd(low), was severely reduced in Fyn-/- compared with conventional lpr mice, whereas division of all other T cell subsets (CD4+, CD8+, and CD4+ B220+) was equal in both types of mice. We conclude that 1) DN lpr T cells, rather than being end stage, retain the capacity to be activated and repeatedly divide before reaching an anergic or replicative senescence stage; 2) the CD3 zeta-chain-associated Fyn kinase is important to DN T cell signal transduction; 3) DN cells, as functional intermediates of the CD8+ subset, are highly dependent on Fas participation for apoptosis; and 4) DN cells contribute to the early development of the serologic and histologic features of the MRL-lpr lupus disease.
Balomenos
D
D
Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Rumold
R
R
Theofilopoulos
A N
AN
D000818:Animals; D000974:Antibodies, Antinuclear / Q000097:blood; D001327:Autoimmune Diseases / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D002455:Cell Division; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation; D008221:Lymphoid Tissue / Q000276:immunology / Q000473:pathology; D008232:Lymphoproliferative Disorders / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D051379:Mice; D019463:Mice, Inbred MRL lpr; D018448:Models, Immunological; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051076:Proto-Oncogene Proteins c-fyn; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D019014:fas Receptor / Q000502:physiology
D000974:Antibodies, Antinuclear; D015704:CD4 Antigens; D016827:CD8 Antigens; D011518:Proto-Oncogene Proteins; D019014:fas Receptor; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D017493:Leukocyte Common Antigens