Natural OX40L expressed on human T cell leukemia virus type-I-immortalized T cell lines interferes with infection of activated peripheral blood mononuclear cells by CCR5-utilizing human immunodeficiency virus

Abstract

BackgroundOX40 ligand (OX40L) co-stimulates and differentiates T cells via ligation of OX40 that is transiently induced on T cells upon activation, resulting in prolonged T cell survival and enhanced cytokine production by T cells. This view has led to the targeting of OX40 as a strategy to boost antigen specific T cells in the context of vaccination. In addition, the ligation of OX40 has also been shown to inhibit infection by CCR5-utilizing (R5) but not CXCR4-utilizing (X4) human immunodeficiency virus type-1 (HIV-1) via enhancement of production of CCR5-binding β-chemokines. It was reasoned that human T cell leukemia virus type-I (HTLV-1) immortalized T cell lines that express high levels of OX40L could serve as an unique source of physiologically functional OX40L. The fact that HTLV-1+ T cell lines simultaneously also express high levels of OX40 suggested a potential limitation.ResultsResults of our studies showed that HTLV-1+ T cell lines bound exogenous OX40 but not OX40L, indicating that HTLV-1+ T cell lines express an active form of OX40L but an inactive form of OX40. Anti-OX40 non-blocking monoclonal antibody (mAb), but not blocking mAb, stained HTLV-1+ T cell lines, suggesting that the OX40 might be saturated with endogenous OX40L. Functionality of the OX40L was confirmed by the fact that a paraformaldehyde (PFA)-fixed HTLV-1+ T cell lines inhibited the infection of autologous activated peripheral blood mononuclear cells (PBMCs) with R5 HIV-1 which was reversed by either anti-OX40L blocking mAb or a mixture of neutralizing mAbs against CCR5-binding β-chemokines.ConclusionsAltogether, these results demonstrated that autologous T cell lines immortalized by HTLV-1 can be utilized as a conventional source of physiologically functional OX40L.

OX 40 ligand newly expressed on bronchiolar progenitors mediates influenza infection and further exacerbates pneumonia

“…To detect α‐2,6 sialic acids or mouse OX40L expression, cells were stained with 100 μg/ml of fluorescein isothiocyanate (FITC)‐conjugated Sambucus nigra agglutinin I and II (SNA, EY Laboratories, San Mateo, CA) or FITC‐conjugated anti‐mouse OX40L monoclonal antibody (clone OX‐89, 1:40) for 1 h at 4°C (Shibuya et al , ). The binding affinities of anti‐human OX40L antibodies (clones W9‐1, W18, W66, 5A8, TAG‐34, 8F4, TARM‐34, HD‐1, and HD‐2) were evaluated by indirect staining with FITC‐conjugated goat‐antibody to rat IgG (for W9‐1, W18, and W66; Abcam, Cambridge, MA), mouse IgG (for 5A8, TAG‐34, 8F4, HD‐1, and HD‐2; Abcam), or mouse IgM (for TARM‐34; Abcam) for 1 h at 4°C (Imura et al , ; Baba et al , ; Kasahara et al , ). Stained cells were analyzed and sorted using a FACSAria II cell sorter and a FACSDiva software (BD Biosciences).…”