Lower numbers of circulating natural killer T (NK T) cells in individuals with human T lymphotropic virus type 1 (HTLV-1) associated neurological disease

• Published in: Clinical and experimental immunology Vol. 158; no. 3; pp. 294 - 299
• Main Authors: Ndhlovu, L.C, Snyder-Cappione, J.E, Carvalho, K.I, Leal, F.E, Loo, C.P, bruno, F.R, Jha, A.R, Devita, D, Hasenkrug, A.M, Barbosa, H.M.R, Segurado, A.C, Nixon, D.F, Murphy, E.L, Kallas, E.G
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.12.2009; Blackwell Publishing Ltd; Blackwell; Blackwell Science Inc
• Subjects: Adult; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Carrier State - immunology; CD4; CD4-Positive T-Lymphocytes - immunology; CD8; CD8-Positive T-Lymphocytes - immunology; Disease Progression; Female; Fundamental and applied biological sciences. Psychology; HTLV-1 infection; HTLV-I Infections - immunology; Human T-lymphotropic virus 1; Humans; immunity; Immunity, Cellular; innate immunity; Lymphocyte Count; Male; Middle Aged; Natural Killer T-Cells - immunology; NK T cells; Paraparesis, Tropical Spastic - immunology; T-Lymphocyte Subsets - immunology; Translational Studies; Young Adult; Human; CD4 T lymphocyte; Natural killer T cell; Deltaretrovirus; Retroviridae; Natural immunity; Nervous system; Biochemistry; HTLV-1 infection; Virus; Natural killer cell; Infection; CD4; innate immunity; CD8; T-Lymphocyte; NK T cells; Suppressive cell; HTLV-I virus; CD8 T lymphocyte
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.2009.04019.x

Human T lymphotropic virus type 1 (HTLV-1) infects 10-20 million people worldwide. The majority of infected individuals are asymptomatic; however, approximately 3% develop the debilitating neurological disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). There is also currently no cure, vaccine or effective therapy for HTLV-1 infection, and the mechanisms for progression to HAM/TSP remain unclear. NK T cells are an immunoregulatory T cell subset whose frequencies and effector functions are associated critically with immunity against infectious diseases. We hypothesized that NK T cells are associated with HAM/TSP progression. We measured NK T cell frequencies and absolute numbers in individuals with HAM/TSP infection from two cohorts on two continents: São Paulo, Brazil and San Francisco, CA, USA, and found significantly lower levels when compared with healthy subjects and/or asymptomatic carriers. Also, the circulating NK T cell compartment in HAM/TSP subjects is comprised of significantly more CD4⁺ and fewer CD8⁺ cells than healthy controls. These findings suggest that lower numbers of circulating NK T cells and enrichment of the CD4⁺ NK T subset are associated with HTLV-1 disease progression.