Recombinant human GM-CSF in myelosuppression of chemotherapy (continued)

Granulocyte colony-stimulating factor and modulation of inflammatory cells in sepsis

Although antimicrobial therapy has been the central clinical strategy for patients with sepsis and multiple organ failure, the survival rate in these patients remains low because their host defense mechanisms usually are compromised. Various inflammatory cytokines recently have been shown to play important roles in normal host defense mechanisms and in sepsis and its sequelae. Cytokine modulation therapies, which have focused on the downregulation of the inflammatory response, have not been shown to benefit these patients. This article examines the role of granulocyte colony-stimulating factor as a proinflammatory mediator and a potential adjuvant treatment in patients with severe infection.

Potentiation by granulocyte macrophage colony-stimulating factor of lipopolysaccharide toxicity in mice

GM-CSF is known to prime leukocytes for inflammatory stimuli in vitro. The objective of this study was to investigate the role of GM-CSF in vivo in a systemic inflammatory reaction syndrome. The results demonstrate a potentiation of LPS toxicity by GM-CSF in a mortality model as well as in a septic liver failure model in mice. Pretreatment of animals with 50 micrograms/kg GM-CSF induced lethality within 24 h in mice challenged with a subtoxic dose of LPS while controls survived > 72 h. A monoclonal anti-GM-CSF antibody significantly protected against a lethal LPS dose. Serum GM-CSF was inducible by LPS and peaked at 2 h. GM-CSF pretreatment dramatically potentiated systemic TNF release and hepatotoxicity induced by a subtoxic dose of LPS in galactosamine-sensitized mice. Potentiation of LPS hepatotoxicity was possible until 30 min after LPS challenge. Polyclonal anti-GM-CSF IgG protected against septic liver failure in this model and attenuated serum TNF concentrations. In vitro an ex vivo experiments revealed that after GM-CSF pretreatment LPS-induced IL-1 release from bone marrow or spleen cells was also enhanced. These findings suggest that GM-CSF represents an endogenous enhancer of LPS-induced organ injury, possibly by potentiating the release of proinflammatory cytokines such as TNF and IL-1.

Recombinant cytokines and pulmonary host defense

The recent discovery of several cytokines and their purification using recombinant DNA technology has uncovered their role as critical factors in pulmonary host defense. The importance of tumor necrosis factor, interferon-gamma, and granulocyte-colony stimulating factor in lung infections was first elucidated in animal models and has been confirmed with neutralization studies. This article reviews these three cytokines, their recent use in human subjects, and their potential use in the future.

Chemotherapy-induced myelosuppression

Chemotherapy-induced myelosuppression is the most common dose-limiting and potentially fatal complication of cancer treatment. Prior attempts to lessen chemotherapy-induced myelosuppression have been minimally effective. The new hematopoietic growth factors show promise, especially for patients requiring intensely myelotoxic chemotherapy. However, a cautious approach should be used with growth factors because their clinical uses and how best to apply each use needs to be defined.

Protection against gram-negative bacteremia in neutropenic mice with recombinant granulocyte-macrophage colony-stimulating factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates production of neutrophils in bone marrow and may decrease the incidence of infection during neutropenia. We evaluated the protective role of recombinant GM-CSF against Pseudomonas aeruginosa challenge in neutropenic mice. CD-1 mice treated with cyclophosphamide on days 1 and 2 of the experiment were given GM-CSF (1, 2, or 4 micrograms/day) starting at day 4 of the experiment according to the following protocol: 1) 1 microgram of GM-CSF 2 hr and 24 hr after challenge; 2) 1 microgram 24 hr before challenge, 2 hr and 24 hr after challenge; 3) 2 micrograms injected 24 hr before and 2 hr after challenge; 4) 2 micrograms given 24 hr before and 2 micrograms given 2 hr and 24 hr after challenge; 5) 4 micrograms administered 2 hr and 24 hr after challenge; and 6) saline and bovine albumin controls. The number of blood neutrophils by days 4 and 5 was similar for GM-CSF-treated and untreated animals. Survival was significantly greater in animals given 2 micrograms of GM-CSF at 24 hr before and at 2 hr and 24 hr after challenge with Pseudomonas. Neutrophils and splenic macrophages obtained from GM-CSF-treated mice (2 micrograms/animal) produced significantly greater amounts of O2- (204 +/- 36 nmoles/10(5) cells) than controls (21 +/- 10 nmoles/10(5) cells). Additionally, neutrophils and macrophages from GM-CSF-treated mice killed significantly more bacteria (P. aeruginosa) in vitro and had a greater number of C3b and Fc receptors (78 +/- 12% and 89 +/- 8%) than did cells obtained from control animals.(ABSTRACT TRUNCATED AT 250 WORDS)