Reactive lymphocyte with dark blue cytoplasm, pleomorphic nucleus, and perinuclear clear zone. Canine.
Morphology: reactive lymphocytes have a heterogenous appearance with variable size, nuclear shape, and amount and color of cytoplasm. Compared to non-reactive lymphocytes, reactive lymphocytes are usually larger with darker blue cytoplasm, darker staining (often pleomorphic) nuclei with no visible nucleoli, perinuclear clear zones, and cytoplasmic vacuoles.
Clinical relevance: reactive lymphocytes in peripheral blood indicate response to antigenic stimulation (bacterial, viral, rickettsial infection or vaccination).
Reactive lymphocyte with dark blue cytoplasm and pleomorphic nucleus. Bovine.Reactive lymphocyte (arrow) with indented nucleus, dark blue cytoplasm, and perinuclear clear zone. Eosinophil (arrowhead – top). Neutrophil (arrowhead – bottom). Canine.Reactive lymphocyte (arrow) with dark blue cytoplasm, indented nucleus, and three pale-staining cytoplasmic inclusions (Russell bodies). Erythrocytes with Howell-Jolly bodies (arrowheads). Canine.Reactive lymphocyte (arrow) with dark blue cytoplasm, pleomorphic nucleus, and perinuclear clear zones. Neutrophil (arrowhead). Artifactual echinocytes also visible (not marked). Canine.
Dr. Cathy Wagg (UCVM)
Dr. Angelica Galezowski (UCVM)
Dr. Nicole Fernandez (WCVM)
Dr. Helene Philibert (WCVM)
Ben Elwood (WCVM)
Dr. Moira Kerr (PDS)
Dr. Sherry Myers (PDS)
Cells and Smears 