Expression of B7 Costimulator Molecules on Mouse Dendritic Cells

Abstract

Dendritic cells are specialized antigen-presenting cells. They are potent, activate quiescent T cells including naive T cells, and function in situ to stimulate different T-dependent immune responses. How do dendritic cells develop, and how do they act as such effective APCs? We like to divide their mechanism of action into three areas. 1] At the level of “signal one,” dendritic cells express high levels of MHC class II products, they can retain antigen following a pulse for days, and they have a vacuolar system that consists of many endosomes rather than scavenging lysosomes. 2] At the level of “signal two,” dendritic cells express many accessory molecules e.g., ICAM-1 & 3 [CD54 & CD50], LFA-1 & 3 [CD11a & CD58], B7-1 & 2 [CD80 & CD86]. 3] A third area relates to in situ properties. Dendritic cells are positioned at locations where antigens enter the body, they efficiently capture antigens in vivo, and they can migrate to the T cell areas to activate naive T cells. Here we emphasize accessory molecules especially the B7 system, a strong stimulator of IL-2 production [Table 1].