Lower numbers of circulating Natural Killer T (NK T) cells in individuals with human T lymphotropic virus type 1 (HTLV-1) associated neurological disease.
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.
Division of Experimental Medicine, Department of Medicine, University of California at San Francisco, San Francisco, CA 94110, USA. lndhlovu@medsfgh.ucsf.edu
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D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002353:Carrier State / Q000276:immunology; D018450:Disease Progression; D005260:Female; D015490:HTLV-I Infections / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D055611:Natural Killer T-Cells / Q000276:immunology*; D015493:Paraparesis, Tropical Spastic / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D055815:Young Adult