Direct ex vivo activation of T cells for analysis of dendritic cells antigen presentation.

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells (APCs) that play a major role in the initiation of immune responses. DC subsets differ in their anatomical locations together with their intrinsic abilities to capture, process, and present antigens on their major histocompatibility (MHC) class I and class II molecules. These features enable each DC subset to have distinct roles in immunity to infection and in the maintenance of self-tolerance. The discrete features of DC subpopulations have largely been defined by cell surface phenotype and anatomical location, rather than function. We have developed direct ex vivo methods to efficiently isolate small numbers of DCs from lymph node (LN) draining tissues and infectious sites to allow fine probing of their function using very sensitive antigen-specific LacZ hybridomas and in vitro proliferation of CFSE-labeled T cells. These approaches are particularly sensitive for detecting endogenous antigens derived from pathogens and self-tissues. Understanding these interactions has begun to allow us to understand how integration of different populations in the DC network responds to multiple scenarios of infection.