Final answer:
The most numerous cell type in the paracortical tissue of a lymph node is the T-cell, which is primarily involved in cellular immune responses.
Step-by-step explanation:
The cell type that is most numerous in the paracortical tissue of a lymph node is the T-cell. The paracortical area is primarily involved with T-cell activity, and it's where T cells interact with dendritic cells. Meanwhile, B cells are typically located in the follicular areas of the lymph node. The fact that B cells differentiate into plasma cells in response to antigen binding and produce soluble antibodies does not relate to the cell number within the paracortical area.
Reviewing the functions of different cell types mentioned, macrophages are phagocytic cells that can both phagocytize pathogens and produce chemicals that promote inflammation. They are found in various parts of the lymph node, but they are not as plentiful as T-cells in the paracortical tissue.