Antigen-specific immunity - Th cell-dependent a cell responses

Helper T cell-regulated B cell responses constitute a major component of th e primary immune response to many pathogens. The subsequent development of antigen-specific immune memory is one critical outcome of this primary adap tive immune response. Antigen-specific immunity develops through a series o f intercellular information exchanges organized around cognate T cell recep torpeptide/MHC interactions. Here, we discuss these complex molecular event s and their cellular consequences in a serial synapsis model of adaptive im munity. Our laboratory has developed strategies to isolate antigen-specific Th cells and B cells to analyze gene expression and cellular function in s ingle responding lymphocytes directly ex vivo. These studies provide insigh t into the regulation and cellular organization of antigen-specific immune responses in vivo.