LC Ndhlovu, JE Snyder-Cappione, KI Carvalho, FE Leal, CP Loo, FR Bruno, AR Jha, D Devita, AM Hasenkrug, HM Barbosa, AC Segurado, DF Nixon, EL Murphy, EG Kallas. (2009). " Lower numbers of circulating Natural Killer T (NK T) cells in individuals with human T lymphotropic virus type 1 (HTLV-1) associated neurological disease. " Clin Exp Immunol. 158, 294-9. PMID: 19778295 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.