title: Comparison of thymocyte development and cytokine production in CD7-deficient, CD28-deficient and CD7/CD28 double-deficient mice.
abstract: CD7 and CD28 are Ig superfamily molecules expressed on thymocytes and mature T cells that share common signaling 0mechanisms and are co-mitogens for T cell activation. CD7-deficient mice are resistant to lipopolysaccharide (LPS)-induced shock syndrome, and have diminished in vivo LPS-triggered IFN-gamma and tumor necrosis factor (TNF)-alpha production. CD28-deficient mice have decreased serum Ig levels, defective IgG isotype switching, decreased T cell IL-2 production and are resistant to Staphylococcus aureus enterotoxin-induced shock. To determine synergistic roles CD7 and CD28 might play in thymocyte development and function, we have generated and characterized CD7/CD28 double-deficient mice. CD7/CD28-deficient mice were healthy, reproduced normally, had normal numbers of thymocyte subsets and had normal thymus histology. Anti-CD3 mAb induced similar levels of apoptosis in CD7-deficient, CD28-deficient and CD7/CD28 double-deficient thymocytes as in control C57BL/6 mice (P = NS). Similarly, thymocyte viability, apoptosis and necrosis following ionomycin or dexamethasone treatment were the same in control, CD7-deficient, CD28-deficient and CD7/CD28-deficient mice. CD28-deficient and CD7/CD28-deficient thymocytes had decreased [3H]thymidine incorporation responses to concanavalin A (Con A) stimulation compared to control mice (P < or = 0.01 and P < or = 0.05 respectively). CD7/CD28 double-deficient mice had significantly reduced numbers of B7-1/B7-2 double-positive cells compared to freshly isolated wild-type, CD7-deficient and CD28-deficient thymocytes. Con A-stimulated CD4/CD8 double-negative (DN) thymocytes from CD7/CD28 double-deficient mice expressed significantly lower levels of CD25 when compared to CD4/CD8 DN thymocytes from wild-type, CD7-deficient and CD28-deficient mice (P < 0.05). Anti-CD3-triggered CD7/CD28-deficient thymocytes also had decreased IFN-gamma and TNF-alpha production compared to C57BL/6 control, CD7-deficient and CD28-deficient mice (P < or = 0.05). Thus, CD7 and CD28 deficiencies combined to produce abnormalities in the absolute number of B7-1/B7-2-expressing cells in the thymus, thymocyte IL-2 receptor expression and CD3-triggered cytokine production.
authors.affiliation: Division of Rheumatology, Allergy and Clinical Immunology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Heinly
authors.forename: G D
authors.initials: GD
authors.lastname: Sempowski
authors.forename: D M
authors.initials: DM
authors.lastname: Lee
authors.forename: D D
authors.initials: DD
authors.lastname: Patel
authors.forename: P M
authors.initials: PM
authors.lastname: McDermott
authors.forename: R M
authors.initials: RM
authors.lastname: Scearce
authors.forename: C B
authors.initials: CB
authors.lastname: Thompson
authors.forename: B F
authors.initials: BF
authors.lastname: Haynes
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D019011:Antigens, CD7 / Q000096:biosynthesis / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D018122:B7-1 Antigen / Q000378:metabolism; D051940:B7-2 Antigen; D018106:CD28 Antigens / Q000096:biosynthesis / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D003208:Concanavalin A / Q000494:pharmacology; D016207:Cytokines / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016853:Muromonab-CD3 / Q000494:pharmacology; D009336:Necrosis; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology
chemical_list: D015703:Antigens, CD; D019011:Antigens, CD7; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D018106:CD28 Antigens; C497965:Cd86 protein, mouse; D016207:Cytokines; D008562:Membrane Glycoproteins; D016853:Muromonab-CD3; D015375:Receptors, Interleukin-2; D003208:Concanavalin A