
Infections, such as influenza, typhus, typhoid, malaria, HIV, tuberculosis or sepsis.
Diseases of the bone marrow.

Enlargement of spleen (spleenomegaly).

Radiation.

Drugs/ Chemicals and solvents - Drugs like Azathioprine are given in transplant patients can cause Leucopenia. Many of the drugs which are used to treat cancer may cause Leucopenia too.

Hypersensitivity to several commonly used medications.

Nutritional - vitaminB12, folate deficiencies Autoimmune diseases (where defense mechanisms of the body acts against its own self rather than a foreign substance).