Blood components are modified to meet the clinical requirements of spe
cific patient populations. The clinical indications for some well-esta
blished components have narrowed with the development of new technolog
y. Leukoreduced blood components are being considered for a variety of
clinical applications. Published data support the use of leukoreduced
components to prevent febrile nonhemolytic transfusion reactions. The
routine use of such components for other indications should be consid
ered experimental, and the cost effectiveness of experimentally valida
ted indications should be evaluated.