A compartment of effector helper and suppressor T cells in the normal mouse thymus.
We have recently described an autonomously activated set of T cells in the spleens of normal and "antigen-free" mice which display effector T helper (TH) or T suppressor (TS) activities; we describe here an intrathymic effector T-cell compartment which directly helps or suppresses B-cell responses and appears to be distinct from the peripheral set of effector cells. Splenic effector T cells do not represent recent thymic migrants (because adult thymectomized mice have unaltered levels of effector TH and TS cells in the spleen), nor do intrathymic effector T cells represent circulating peripheral T cells (since thymic effector T cells are B2A2+, while splenic effector T cells are B2A2-). Furthermore, effector TH cells within the two compartments exert differential effector activities: splenic effector TH cells induce B cells to both proliferation and maturation, while thymic effector TH cells are defective in activating B-cell maturation. The present findings extend our studies on "natural" lymphocyte activities in the normal immune system, revealing the existence of two apparently distinct effector T-cell compartments. The potential significance of the intrathymic set of effector cells in repertoire selection is considered.
Larsson-Sciard
E L
EL
Department of Immunology, University of Stockholm.
Coutinho
A
A
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D007113:Immunity, Innate; D008213:Lymphocyte Activation; D051379:Mice; D013154:Spleen / Q000166:cytology / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000145:classification / Q000166:cytology* / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000145:classification / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology
D000945:Antigens, Differentiation, T-Lymphocyte