They may migrate into extravascular tissues where they may be stimulated by complexes of antigens that are bound to IgE. Monocytes Monocytes are larger than other leukocytes, and they mature into macrophages once they are released into the bloodstream. Monocytes then migrate to tissues, particularly the liver, lymph nodes, and lungs, where they may stay for days or years. Here, the monocytes are actively phagocytic, and they ingest particulate matter. Monocytes are also important to the immune response. B-cells are characterized by the presence of immunoglobulins on their surface, and upon stimulation with antigen, they are transformed into plasma cells.
Plasma cells are then able to secrete antibodies specific to the antigen.
T-cells take part in cell mediated immune response, which does not depend on the presence of circulating antibodies.