Thank Goodness for B-Cells! B-Cells are a type of white blood cell within the lymphocyte category. They play a crucial role in immune function by fighting off trespassing invaders such as viruses. Upon contact with a pathogen, it records the unique microbial shape & creates a specialized protein structure, or antibody, to disable the foreign intruder upon subsequent exposure. This is why we don’t contract illness from a cold or flu virus more than once.