Hematology 1 Practice Test

Platelet satellitism is an in vitro artifact seen in EDTA-treated blood where platelets form rosettes around neutrophils on a peripheral smear. This happens because autoantibodies against platelet antigens coat the platelets, and the Fc portion of those antibodies interacts with Fc receptors on neutrophils, pulling platelets to the neutrophil surface. The result is platelets adhering to neutrophils, giving the characteristic satellites. This can cause a falsely low platelet count in automated measurements, since platelets are bound to leukocytes rather than counted as free platelets. Using a different anticoagulant (like citrate or heparin) or warming the sample often dissolves the rosettes and normalizes the count.