The measurement of granulocyte kinetics

Chemotherapy and neutropenia

Myelosuppression is the most common toxicity associated with the administration of dose-intensive cytotoxic chemotherapy. The basic understanding of neutrophil biology and the physiology of chemotherapy-induced neutropenia has advanced tremendously in the past 2 decades. Concordantly, the ability to reduce the morbidity associated with neutropenia has improved. Adjunctive cytokine and progenitor cell support of hematologic recovery after myelosuppressive therapy have proved to be models of translational research and have led to novel therapeutic initiatives for patients with cancer and hematologic malignancies. In this article, fundamental aspects of neutrophil production are discussed, and the clinical development of hematopoietic cytokines active on cells of the leukocyte lineages is presented.

Granulocyte transfusions in neutropenic patients

Patients with severe neutropenia are at increased risk for systemic infection with bacteria or fungi. This risk is in proportion to both the degree and duration of the neutropenic process. Although granulocyte transfusion as a means of augmenting host defenses would appear to be a logical therapeutic intervention in clinical contexts involving severe and prolonged neutropenia, several features of granulocyte physiology and collection complicate such considerations. These include the large numbers of granulocytes normally produced by healthy hosts, the short survival of the granulocyte in the circulation after transfusion, the relatively small number of granulocytes which can be collected using currently available pheresis techniques, problems associated with alloimmunization, and the possibility of transferring disease (CMV, toxoplasmosis, hepatitis) by means of these transfusions. In the mid-1970s, well-designed clinical studies strongly suggested that patients with documented Gram-negative sepsis or tissue infection that failed to respond to appropriate antibiotics were significantly benefited by granulocyte transfusions. With recent advances in potent, broad-spectrum antibiotic availability, some have questioned whether these observations remain valid. Several studies regarding the prophylactic use of granulocyte transfusions in patients undergoing allogeneic bone marrow transplantation and/or induction therapy for leukemia have failed to reveal therapeutic benefits and suggested the possibility of significant side effects. These studies are reviewed.

Polymorphonuclear leukocyte accumulation in brain regions with low blood flow during the early postischemic period

In an anesthetized canine model in which ischemia was induced by incremental air embolism, 16 animals were exposed to 1 hr of ischemia and monitored for 10 min (n = 4), 60 min (n = 6), or 240 min (n = 6). Fourteen animals were observed for corresponding periods without being subjected to ischemia 70 min (n = 4), 120 min (n = 4), or 300 min (n = 6). Autologous granulocytes were labeled with 111In and reinfused just before ischemia. At the conclusion of each experiment, a 14C-iodoantipyrine autoradiographic blood flow study was performed. Granulocyte accumulation measured by gamma scintigraphy (cpm/gm) occurred in the injured hemisphere of ischemic animals at 60 min in anterior brain segments and at 240 min in anterior, middle, and posterior segments. By means of a double-label autoradiography technique, clustering of punctate granulocyte images was detected in regions of low flow or heterogeneous flow in half of the animals at both 60 min and 240 min postischemia. Granulocyte clustering did not occur in the autoradiograms of nonischemic animals. The results implicate granulocyte participation in the acute phase of ischemic brain injury and signal a convergence of hemostatic and inflammatory processes during the immediate postischemic period.

Labeled cells in the investigation of hematologic disorders

Radiolabeling techniques for white cells, platelets, and erythrocytes are reviewed. The early studies using diisopropylfluoro-32P contributed to an understanding of the production and circulation of the blood elements, and 51Cr proved useful in localizing sites of cell migration or destruction. 111In-oxine has further improved the understanding of blood cell organ sequestration, and permitted combined kinetic and organ imaging studies. Radionuclide labels have been essential for the elucidation of various hematologic disorders, such as the neutropenias, thrombocytopenias, anemias, and polycythemia. Many new treatments, including monoclonal antibodies, have been evaluated with radionuclides.