Lymphocytes are found in the lymph,
a colorless, watery fluid in the lymph vessels.
The lymph vessels are part of the lymph system,
which is made up of thin tubes that branch,
like blood vessels, into all parts of the body.

Along this network of vessels are groups of small,
bean-shaped organs called lymph nodes.
Clusters of lymph nodes are found in the underarm,
pelvis, neck, and abdomen.
The spleen (an organ in the upper abdomen that makes lymphocytes
and filters old blood cells from the blood),
the thymus (a small organ beneath the breastbone),
and the tonsils (an organ in the throat)
are also part of the lymph system.

Lymphocytes fight infection by making antibodies,
which attack germs and other harmful bacteria
in the body. In chronic lymphocytic leukemia,
the developing lymphocytes do not mature
correctly and too many are made. The lymphocytes may
look normal, but they cannot fight
infection as well as they should. These immature
lymphocytes are then found
in the blood and the bone marrow.
They also collect in the lymph tissues and make them swell.

Lymphocytes may crowd out other blood cells
in the blood and bone marrow.
Anemia may develop if the bone marrow
cannot make enough red blood cells to carry oxygen.
If the bone marrow cannot make enough platelets
to make the blood clot normally,
bleeding or bruising may occur easily.