Non-antigen specific CD8+ T suppressor lymphocytes.
The homeostasis of peripheral immune system function is maintained by the activity of regulatory lymphocytes. Among these cells, a subset of CD8+CD28- T suppressor lymphocytes has recently been characterized for the capacity to mediate their effects without antigen restriction. These non-antigen-specific CD8+ T suppressor lymphocytes originate from circulating CD8+CD28- T lymphocytes after stimulation with interleukin-2 and interleukin-10. CD8+ suppressor cells inhibit both antigen-specific CD4+ T cell proliferation and cellular cytoxicity through secretion of cytokines such as interferon-gamma, interleukin-6, and interleukin-10. The function of CD8+ suppressor cells is impaired in patients with systemic lupus erythematosus in relapse as well as in patients with systemic sclerosis with disease progression, suggesting the involvement of CD8+ suppressor cells in the pathogenesis of autoimmune diseases. Interestingly, CD8+ suppressor cells have been found among tumor-infiltrating lymphocytes, which could be related to tumor-induced-immunosuppression. Failure to generate CD8+ suppressor cells from the peripheral blood is frequently observed in HIV-infected patients. It remains to be clarified whether this phenomenon is due to depletion and/or functional impairment of this cell subset or to their compartmentalization in peripheral tissues and immunocompetent organs where they could contribute to the induction of immunodeficiency.
Filaci
G
G
Department of Internal Medicine (DIMI) and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Viale Benedetto XV n.b., I-16132 Genoa, Italy. gfilaci@unige.it
Fravega
M
M
Fenoglio
D
D
Rizzi
M
M
Negrini
S
S
Viggiani
R
R
Indiveri
F
F
D000818:Animals; D006412:Hematopoietic Stem Cells / Q000502:physiology; D006801:Humans; D016130:Immunophenotyping; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D012595:Scleroderma, Systemic / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000502:physiology*