Leukocytes: White Blood Cells that help the body fight infections and other diseases. Also called white blood cells (WBCs). From Healthy Resources One Clinical Trial to Long-Term RemissionGood vs Bad Advice for Type 2 DiabetesYour EGFR-Positive NSCLC Treatment Options Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew