White blood cell count (WBC count)

White blood cell (WBC) count is a fundamental clinical laboratory measurement that quantifies the total number of leukocytes per microliter of blood, serving as a primary indicator of immune system status [NIH/MedlinePlus]. It is not a molecular target in the pharmacological sense but rather a composite biomarker reflecting the populations of neutrophils, lymphocytes, monocytes, eosinophils, and basophils [StatPearls]. The count is used extensively to diagnose and monitor infections, inflammatory conditions, and hematologic malignancies such as leukemia [Mayo Clinic]. Pharmacological agents frequently influence the WBC count; for instance, colony-stimulating factors are administered to treat neutropenia by enhancing bone marrow production, while many chemotherapeutic drugs cause a decrease in WBC count as a toxic side effect. Clinically, monitoring the WBC count is essential for assessing the safety profiles of drugs with known hematologic risks, such as clozapine or carbamazepine. As a diagnostic parameter, it provides critical insight into a patient's physiological response to both disease and therapeutic intervention.

Other names

Leukocyte countTotal white countWBCLeukocyte number

Drugs do not bind to the 'count' itself; instead, they modulate the production of leukocytes via growth factor receptors (e.g., G-CSF receptor), deplete populations through cytotoxic effects on marrow precursors, or redistribute cells from tissues to the bloodstream (e.g., demargination via glucocorticoids).