Immunology lesson focusing on the activation of dendritic cells, migration to secondary lymphoid tissue, antigen presentation, and the role of B and T cells. The lesson also covers the function of chemokine receptor CCR7, the activation of dendritic cells by chemokines, and the migration of naive T cells to the paracortex. Additionally, information on the spleen, its location, function, and potential dysfunctions like postsplenectomy findings are discussed.