LIGHT, a new TNF superfamily member, is essential for memory T helper cell‐mediated activation of dendritic cells

Abstract

LIGHT is a recently identified member of the TNF superfamily that is up-regulated on activated T cells and can cooperate with CD40L to condition DC for the priming of CTL. In this report, we show that an intracellular pool of LIGHT is found selectively in some CD45RA -CD27 + CD4 + "central" memory T cells and to a greater extent in some CD45RA -CD27 -CD4 + effector memory T cells. LIGHT, like CD40L, is rapidly up-regulated on memory CD4 + T cells upon activation. Unlike CD40L, LIGHT up-regulation on naive T cells is delayed. Stimulation of DC with each subset of memory T cells in the presence of superantigen revealed that CD40L and LIGHT are required for optimal secretion of IL-12. Moreover, effector memory T cells, which can interact with DC in peripheral tissues, contribute to CCR7 induction on DC. LIGHT and CD40L can also regulate IL-12 production by CCR7 + DC capable of migration to lymph nodes. These data suggest that both LIGHT and CD40L may be involved in the maintenance or reactivation of secondary Th1 responses.

LIGHT Is Constitutively Expressed on T and NK Cells in the Human Gut and Can Be Induced by CD2-Mediated Signaling

“…1C, 2C, and 7), suggesting that LIGHT expression is regulated at the transcriptional level. Alternatively, intracellular stores of LIGHT have been reported (43), proposing a presynthesized protein pool that can be rapidly transported to the cell surface. Our data indicate that LIGHT induction is actinomycin D and CHX sensitive (Fig.…”

“…Furthermore, full-length LIGHT mRNA was not detected in unstimulated T cells (Figs. 5C and 6C), but a variant form of LIGHT has been described that lacks the transmembrane domain and cannot be displayed on the cell surface (29), most likely accounting for intracellular LIGHT detected in resting PB T cells (43). However, a more precise real-time protein-trafficking analysis will be required to exclude intracellular stores of LIGHT as a mechanism for rapid induction and to establish whether signaling activity may be terminated by shedding LIGHT (29).…”

LIGHT costimulates CD40 triggering and induces immunoglobulin secretion; a novel key partner in T cell‐dependent B cell terminal differentiation

“…CD40L/CD154, CD134 and CD70. Nonetheless, the TNFR/TNF family has more than 20 members, and our studies [1][2][3] have particularly focused our attention on the herpes virus entry mediator (HVEM) and its ligand LIGHT (homologous to lymphotoxin, inducible expression, competing for GpD of herpes virus, that binds to the HVEM, and is expressed on activated T lymphocytes). The HVEM molecule has a broad expression in hematopoietic cells, i.e.…”

Ação da pentoxifilina nos dendrócitos dérmicos FXIIIa de placas de psoríase

“…O aumento da população de dendróci-tos dérmicos Fator XIIIa+, observado após o tratamento com a PTX, poderia ser explicado, então, pela manutenção do estímulo tecidual para sinalização e migração de precursores de células dendríticas, uma vez que os processos etiopatogenéticos não seriam afetados pela droga. 24,[33][34][35][36][37][38][39][40] O questionamento sobre o aumento do núme-ro de mastócitos e sua degranulação na placa psoriá-sica após o tratamento, sem a repercussão clínica de prurido e histaminemia, ainda está para ser respondido. Seriam os mecanismos fisioimunopatogênicos da degranulação causada pela imunomodulação diferentes daquele que ocorre na reação de hipersensibilidade do tipo I?…”