Abstract
Human T lymphotropic virus type I (HTLV-I) impairs cellular immunity and can develop into adult T cell leukemia/lymphoma (ATLL). The Role of dendritic cells (DC) has not been fully elucidated in individuals infected by HTLV-I. To address this issue, we studied several cellular parameters, including phenotypic and functional characteristics of monocyte-derived DC. Generated DC exhibited down-regulation in the expression of CD1a and HLA-DR in HTLV-I carriers, suggesting partial impairment of maturation. T cells were stimulated by autologous DC in half of HTLV-I carriers, as well as healthy donors, but not in ATLL patients. Because of the importance of CD40-CD40 ligand (CD40L) signaling in establishing an inflammatory immune response, we also investigated the expression of soluble CD40L (sCD40L) of PHA-activated lymphocytes from HTLV-I infected individuals. sCD40L was detected in the culture supernatant of lymphocytes from one of four HTLV-I carriers investigated. These results suggest that the defect or aberration in the function of DC and the expression of sCD40L in T cells is associated with immune suppression in HTLV-I infected individuals.
