B cells are an important part of our immune system. They help protect us from illnesses by making antibodies and remembering past infections.

What Are B Cells?

• B cells start from special cells in our bone marrow called hematopoietic stem cells.
• They can grow into two types: naive B cells or memory B cells.

How Do B Cells Make Antibodies?

• When a B cell spots a harmful invader, like a virus or bacteria (this is called an antigen), it needs help to get started. It usually gets help from another kind of immune cell called CD4+ T cells.
• Once activated, these B cells multiply and change into plasma cells.
• Plasma cells are like tiny factories! One of them can make about 2,000 antibodies every second. These antibodies are important because they help to fight off germs.

What Is Immunological Memory?

• After fighting off an infection, some B cells turn into memory B cells. These cells can stick around for a long time—sometimes even decades!
• If the same germ tries to attack us again, memory B cells react much faster than the first time we encountered it. They can produce antibodies up to 100 to 1,000 times quicker than before.
• This is why we often don’t get sick again after having an illness or getting vaccinated. Even as memory B cell numbers decrease over time, they can still help protect us for many years.

In short, B cells are essential for our adaptive immune system. They make antibodies and help us remember past infections, keeping us safe from getting sick again.