Phagocytosis and burst activity of granulocytes and monocytes after stem cell transplantation

In addition to a low number of leukocytes, an impairment of leukocyte function can also contribute to the increased susceptibility to bacterial and fungal infection in marrow transplant recipients. Phagocytosis and oxidative burst activity were measured in patients at various stages after transplant by using assay systems that are based on the quantification of the immunofluorescence of ingested bacteria. Although phagocytosis was normal in most transplant recipents, the oxidative burst of granulocytes was significantly impaired in recipients early after autologous and allogeneic transplants. Patients who underwent tests in later stages after transplant had normal leukocyte function test results. These observations are compatible with the notion that recipients early after bone marrow transplant may be able to phagocytize bacteria readily but that their ability to inactivate them via the oxidative burst might be compromised.