Here is a discrete question that I am having trouble understanding: The spleen can be considered the largest lymph node, even though it is not part of the lymphatic system. Like all lymph nodes, the spleen: A. acts as a blood reservoir for the circulatory system. B. intercepts antigenic agents in the circulating blood. C. is composed entirely of large aggregates of lymphocytes. D. contains the cells responsible for humoral and cell-mediated immunity. So the correct answer is D. I have a few concerns pertaining to this answer: 1. In what way is B wrong? I thought foreign antigen-containing particles interact with B-cells at the lymph nodes. Am I wrong? 2. I thought that lymph nodes contained primarily B-cells. Do they also contain T-cells? All I know about T-cell localization is that they mature in the thymus. So do they end up being stored in lymph nodes after maturation? I guess the fact that T-cells are considered lymphocytes indicates that they are in some way related to lymph nodes. Any help is appreciated!