[GM-CSF and G-CSF: cytokines in clinical application].

Leukopenia or pancytopenia as a result of bone marrow dysfunction are manifestations of various diseases or complications of therapeutic regimens. The spectrum of diseases associated with leukopenia is wide and includes congenital as well as acquired neutropenias secondary to conditions such as myelodysplastic syndromes, AIDS, malignant tumors with or without chemotherapy-enhanced neutropenia, bone marrow transplantation or therapeutic or accidental radiation. The morbidity and mortality of infectious diseases is greatly enhanced during neutropenic phases. Over the last few years attempts have been made to shorten the duration and lessen the severity of neutropenia in patients with the above conditions by administration of Granulocyte Macrophage Colony Stimulating Factor (G-CSF). Both cytokines were successfully tested in phase I and II trials. Treatment with GM-CSF or G-CSF results in a dose-dependent increase of the neutrophil count. GM-CSF also increases the number of eosinophils and monocytes in peripheral blood. The effect of both cytokines on the neutrophil count is transient as long as the underlying disease persists. This prompted the institution of maintenance therapy, which has been successfully used with either cytokine. Long-term treatment is usually well tolerated and results in a reduction in the frequency of infections as well as in the duration of antibiotic treatments. Side effects of GM-CSF or G-CSF are usually mild and include fever, myalgia, bone pain, and erythema. A number of patients developed dyspnea, hypotension, sweating, flushing and erythema after the first dose of GM-CSF in each treatment cycle. This first-dose reaction occurs more frequently after intravenous than reactions were reported with G-CSF. Some patients with myelodysplastic syndrome progressed to acute myeloic leukemia during or after treatment with GM-CSF or G-CSF. Most of these patients presented with an increased fraction of blasts in the bone marrow, which preceded the treatment with the colony stimulating factors. Since GM-CSF and possibly G-CSF may increase the risk of developing acute leukemia in patients with myelodysplastic syndrome, it appears prudent to limit the use of these cytokines in patients with this disease. The subcutaneous route of administration appears to be preferable to intravenous administration, since the incidence and severity of side effects are reduced. While many questions concerning dosage, long-term therapy and combination therapy still remain unanswered, the information presented in this review concerning the clinical use of these cytokines warrants an optimistic outlook.