Privilege of immunity.

(From Philippine Daily Inquirer)

Byline: Massie Santos Ballon

IN AN EPISODE of "The Simpsons," Bart is infected with germs that try to make him sick. The white blood cells line up to face the enemy, defending his body against the invaders until Bart makes it clear that he wants to be sick so he can miss school. Learning this, the entire army of the immune system lies down and lets the germs take over.

Not all white blood cells handle the duties of protecting the body against disease; this is a job for B cells, which originate from and mature in the bone marrow, and T cells, which originate from the bone marrow but mature in the thymus.

When B cells are activated by certain T cells, they can recognize a particular germ and make antibodies to protect the human body. Similarly, the receptors of cytotoxic T cells can hone in on a specific cell and destroy it, which is useful when combating diseases such as AIDS and cancer.

Forming T cells

The antibodies produced by B cells come from the immunoglobulin (Ig) family which has many branches or isotypes such as IgM, IgG, IgD. It was always assumed that B cells and T cells originated separately in the bone marrow, but a new study suggests that B cells play a role in the formation of T cells.