# B Cells As with nearly all [[cells of the immune system]], these cells are capable of **differentiating** into more specific variations **Plasma cells** are differentiated B cells that secrete soluble antibodies that target extracellular pathogens - they are not phagocytes and do not perform phagocytosis **Naïve lymphocytes** have not yet encountered their specific antigen - Sometimes referred to as *virgin lymphocytes* ## B Cell Structure The morphology of B Cells can drastically change over it's lifespan A plasma cell's interior is almost entirely filled by their [[endoplasmic reticulum]]. - The sole purpose of plasma cells is to produce [[Antibodies|antibodies]] (which are [[proteins]]), the endoplasmic reticulum is significantly larger than that of any other cell to amplify that production process. ## Life Cycle of B Cells - [ ] Where are B-Cells at each step of their development/maturation/activation - If we were to take a ### Development > Immature B Cells only have **IgM** while mature B Cells also have **IgD** > "It goes to college and obtains its M.D. when it matures" When an antigen binds to an immunoglobulin (BCR), the B-Cell will proliferate (multiply) and differentiate into plasma cells Plasma Cells are the terminally differentiated cells (last stage in development) that originate from B-Cells ### Maturation ### Activation ---