Overview of Leukopenias
Leukopenia is a reduction in the circulating WBC count to < 4000/μL. It is usually characterized by a reduced number of circulating neutrophils, although a reduced number of lymphocytes, monocytes, eosinophils, or basophils may also contribute. Thus, immune function is generally decreased.
Neutropenia is a reduction in blood neutrophil count to < 1500/μL in whites and <1200/μL in blacks. It is sometimes accompanied by monocytopenia and lymphocytopenia, which cause additional immune deficits.
Lymphocytopenia, in which the total number of lymphocytes is < 1000/μL in adults, is not always recognized as a decrease in the total WBC count because lymphocytes account for only 20 to 40% of the total WBC count. The consequence of the lymphopenia can depend on the lymphocyte subpopulation(s) that are decreased.
Monocytopenia is a reduction in blood monocyte count to < 500/μL. Monocytes migrate into the tissues where they become macrophages, with characteristics depending on their tissue localization.