The driven by the increased association of adhesion molecules to maintain contact between T cells and dendritic cells

Is linked to the innate feature of the dendritic cells that involves Pattern recognition receptors and their recognition of pathogen structures.

Occurs once all the surface interactions between Dendritic cell and T cell have occurred and is indicating the activation of intracellular signal transduction pathways.

Refers specifically to the cytokines that are released by dendritic cells to drive the second aspect of activation which is differentiation to a T helper subset.