Modeling T cell-antigen presenting cell interactions.

We present and analyze a model for the interaction of naive T cells with antigen presenting cells (APCs) that results in T-cell activation. We use this model to examine delayed type hypersensitivity (DTH) reactions. We show that responses can be of two types; either the antigen is completely eliminated or the immune system fails to eliminate the antigen and chronic infection results. Both outcomes are characteristic of diseases in which delayed type hypersensitivity is the primary defense mechanism. We compare the effectiveness of two types of APCs macrophages and dendritic cells, in the generation of DTH responses. We conclude that dendritic cells are more suited to the task of stimulating naive T cells than are macrophages, as has recently been argued by Steinman and coworkers.