Final answer:
Reactive lymphocytes have a large amount of rough endoplasmic reticulum (RER) in their cytoplasm, which allows them to secrete soluble antibodies.
Step-by-step explanation:
Lymphocytes are the primary cells of the adaptive immune response. B cells and T cells are the two basic types of lymphocytes. They have a large central nucleus surrounded by a thin layer of cytoplasm.
Reactive lymphocytes are a type of B or T cell that have become activated in response to antigen binding.
They can be identified by their cytoplasmic characteristics, which include a large amount of rough endoplasmic reticulum (RER).
Plasma cells are a type of reactive B cell that have differentiated in response to antigen binding.
They have a large amount of cytoplasm packed with RER, which allows them to secrete soluble antibodies.