T-lymphocyte downregulation after acute viral infection is not dependent on CD95 (Fas) receptor-ligand interactions.
Infection of mice with lymphocytic choriomeningitis virus (LCMV) causes a major expansion of CD8+ T cells followed by a period of immune downregulation that coincides with the induction of lymphocyte apoptosis in the mouse spleen. CD95 (Fas) and its ligand are important for regulating peripheral T-lymphocyte numbers and can mediate apoptosis of mature T lymphocytes. We infected CD95- and CD95L-deficient mice (lpr and gld, respectively) with LCMV to determine if the immune downregulation that occurred following resolution of the LCMV infection was due to a CD95-dependent apoptotic mechanism. Lymphocytes from LCMV-infected lpr and gld mice were capable of normal T-cell expansion and cytolytic function but were, in contrast to activated cells from normal virus-infected mice, relatively more resistant to T-cell receptor-induced apoptosis in vitro. However, in vivo there were significant numbers of apoptotic cells in the spleens of lpr and gld mice recovering from the infection, and the T-cell number and cytolytic activity decreased to normal postinfection levels. Thus, CD95 is not required for the immune downregulation of the CD8+-T-lymphocyte response following acute LCMV infection.
Department of Pathology, University of Massachusetts Medical Center, Worcester 01655, USA.
B L
BL
Lohman
E S
ES
Razvi
R M
RM
Welsh
D000208:Acute Disease; D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D015536:Down-Regulation / Q000276:immunology*; D053222:Fas Ligand Protein; D008216:Lymphocytic Choriomeningitis / Q000276:immunology*; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology*; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D019014:fas Receptor / Q000276:immunology*
D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D019014:fas Receptor