Leukopenia

A clinical condition known as leukopenia occasionally

occurs in which the bone marrow produces very few

white blood cells, leaving the body unprotected against

many bacteria and other agents that might invade the

tissues.

Normally, the human body lives in symbiosis with

many bacteria, because all the mucous membranes of

the body are constantly exposed to large numbers of

bacteria. The mouth almost always contains various

spirochetal, pneumococcal, and streptococcal bacteria,

and these same bacteria are present to a lesser extent

in the entire respiratory tract. The distal gastrointestinal

tract is especially loaded with colon bacilli. Furthermore,

one can always find bacteria on the surfaces

of the eyes, urethra, and vagina. Any decrease in the

number of white blood cells immediately allows invasion

of adjacent tissues by bacteria that are already

present.

Within 2 days after the bone marrow stops producing

white blood cells, ulcers may appear in the mouth

and colon, or the person might develop some form of

severe respiratory infection. Bacteria from the ulcers

rapidly invade surrounding tissues and the blood.

Without treatment, death often ensues in less than a

week after acute total leukopenia begins.

Irradiation of the body by x-rays or gamma rays, or

exposure to drugs and chemicals that contain benzene

or anthracene nuclei, is likely to cause aplasia of the

bone marrow. Indeed, some common drugs, such as

chloramphenicol (an antibiotic), thiouracil (used to

treat thyrotoxicosis), and even various barbiturate

hypnotics, on very rare occasions cause leukopenia,

thus setting off the entire infectious sequence of this

malady.

After moderate irradiation injury to the bone

marrow, some stem cells, myeloblasts, and hemocytoblasts

may remain undestroyed in the marrow and are

capable of regenerating the bone marrow, provided

sufficient time is available.A patient properly treated

with transfusions, plus antibiotics and other drugs to

ward off infection, usually develops enough new bone

marrow within weeks to months for blood cell concentrations

to return to normal.