Here's a breakdown:

* B cells are a type of white blood cell that mature in the bone marrow. They are responsible for humoral immunity, which is the part of the immune system that uses antibodies to fight infections.

* When a B cell encounters an antigen (a foreign substance like a virus or bacteria), it differentiates into a plasma cell.

* Plasma cells are specialized B cells that produce and secrete large amounts of antibodies. These antibodies then bind to the antigen, marking it for destruction by other immune cells.

So, while other immune cells play important roles in fighting infections, B cells are the primary source of antibodies.