title: TNF regulates thymocyte production by apoptosis and proliferation of the triple negative (CD3-CD4-CD8-) subset.
abstract: TNF is a proinflammatory cytokine with opposing death/no-death effects in vivo and in vitro. Our studies showed that TNF regulates mouse thymocyte production, inducing both apoptosis and proliferation of the most immature CD3(-)CD4(-)CD8(-) triple negative (TN) subset within a broad range of dosages (10(1)-10(5) pg/ml) in the presence of IL-7. TNF apoptosis affected only the TN3 (CD44(-)CD25(+)) and TN4 (CD44(-)CD25(-)) subsets that expressed both TNFR-p55 and -p75. Although each TNFR alone could mediate TNF apoptosis, maximal apoptosis was seen in C57BL/6J wild type, which expressed both TNFRs. TNF also induced proliferation of TN3 cells at higher doses (10(4)-10(5) pg/ml) mediated only by TNFR-p75. Both anti-TNFR-p55 and -TNFR-p75 mAb inhibited apoptosis but only anti-p75 inhibited proliferation. TNF also regulated TN proliferation to IL-7 because TNFR knockout (KO), TNF KO, and TNF/lymphotoxin alpha and beta triple KO mice showed 2- to 3-fold increased responses not seen in C57BL/6J wild type. In vivo, TNFR KO mice showed thymic hypertrophy with a 60% increase in total thymocytes, with no effect on the CD4/CD8 subsets. We conclude that TNF maintains homeostatic control of total thymocyte production by negative selection of TN3 and TN4 prothymocytes and down-regulation of their proliferation to endogenous IL-7.
authors.affiliation: Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. jmgonzal@aecom.yu.edu
authors.forename: J G
authors.initials: JG
authors.lastname: Baseta
authors.forename: O
authors.initials: O
authors.lastname: Stutman
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D017252:CD3 Complex / Q000096:biosynthesis; D015704:CD4 Antigens / Q000096:biosynthesis; D016827:CD8 Antigens / Q000096:biosynthesis; D002453:Cell Cycle / Q000235:genetics / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D006984:Hypertrophy; D015851:Interleukin-7 / Q000494:pharmacology; D007700:Kinetics; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D008233:Lymphotoxin-alpha / Q000235:genetics; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000172:deficiency / Q000235:genetics / Q000276:immunology / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D018960:Hyaluronan Receptors; D015851:Interleukin-7; D008233:Lymphotoxin-alpha; D015375:Receptors, Interleukin-2; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha