Review of a white blood cell count suggests a viral infection when which component is elevated?

Review of a white blood cell count suggests a viral infection when which component is elevated?

• A. Bands
• B. Leukocytes
• C. Lymphocytes
• D. Neutrophils

Answer: (C)

Viral infections typically cause lymphocytosis on the white blood cell differential. Lymphocytes are the immune cells—T cells and B cells—that target virus-infected cells and produce antibodies. When a viral illness is present, these cells proliferate, increasing the lymphocyte count either in absolute terms or as a higher percentage of total white cells. Elevations of bands or neutrophils point more toward a bacterial infection or a stress response, because that neutrophil lineage is the first line of defense against bacteria and tissue injury. The total leukocyte count is less specific, as it can rise with various infections, inflammation, or other stresses. So seeing an elevated lymphocyte count specifically supports a viral rather than a bacterial process.

Viral infections typically cause lymphocytosis on the white blood cell differential. Lymphocytes are the immune cells—T cells and B cells—that target virus-infected cells and produce antibodies. When a viral illness is present, these cells proliferate, increasing the lymphocyte count either in absolute terms or as a higher percentage of total white cells.

Elevations of bands or neutrophils point more toward a bacterial infection or a stress response, because that neutrophil lineage is the first line of defense against bacteria and tissue injury. The total leukocyte count is less specific, as it can rise with various infections, inflammation, or other stresses.

So seeing an elevated lymphocyte count specifically supports a viral rather than a bacterial process.