I'm interested in how dendritic cells present antigens to helper T-cells? I'm also interested in the molecular actions between a dendritic cell and a helper T-cell during the activation of the helper T-cell? What function does the homing receptor on a T-cell have?
Dendritic cells are so called professional antigen-presenting cells (APCs) as pointed out by Sleepes in comment section. They express both MHC-I and MHC-II receptors on their cell surface on which they present small peptides. These small peptides come from digested proteins of their own (MHC-I) or antigens that were phagocited or taken up by receptor mediated endocytosis (MHC-II). They also express costimulatory molecules necessary for the activation of T-cells (eg. CD80/CD86).
As you can see in image above, activation of a T-cell requires two distinct signals: the recognition of an antigen and a co-stimulatory signal.
After activation T-cells undergo rapid division and diversification.
Details of T-cell activation by dendritic cells can be found in this article for example: Immunol Cell Biol. 1997 Jun;75(3):223-30. The role of dendritic cells in T cell activation. Ni K1, O'Neill HC.