Biological properties in vitro of a combination of recombinant murine interleukin-3 and granulocyte-macrophage colony-stimulating factor

Retrospective analysis of infectious disease in patients who received recombinant human granulocyte-macrophage colony-stimulating factor versus patients not receiving a cytokine who underwent autologous bone marrow transplantation for treatment of lymphoid cancer

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) significantly shortens the number of days required to achieve an absolute neutrophil count of >500/mm3 after autologous bone marrow transplantation (ABMT); however, the ability of rhGM-CSF to enhance neutrophil and macrophage function in vivo has been incompletely characterized. In this retrospective study, the authors compared the incidence of infection from the day of transplantation to 28 days posttransplantation between two groups of previously studied patients who underwent ABMT at the Fred Hutchinson Cancer Research Center. A control group that received no cytokine was compared with a study group that received rhGM-CSF while participating in phase I, II, or III trials. During the posttransplantation period when both study groups had severe neutropenia, 40% (38 of 95) of control patients were found to have an infection, whereas only 13% (6 of 46) of rhGM-CSF patients developed an infection (p = 0.001). Most infections occurred before an absolute neutrophil count of > 100/mm3 was achieved. There was a trend toward fewer fungal infections (14% vs. 4%; p = 0.093); gram-negative bacterial infections (6% vs. 0%; p = 0.083); pulmonary infections (12% vs. 2%; p = 0.062); fewer days of amphotericin B (p = 0.0305); and fewer days of intravenous antibiotics (p = 0.0791) in rhGM-CSF-treated patients. These results support in vivo findings that the function-enhancing effect of rhGM-CSF may reduce infection-related complications.

Increased C3 production in human monocytes after stimulation with Candida albicans is suppressed by granulocyte-macrophage colony-stimulating factor

Activation of the complement system is an important part of host resistance against fungal infections. When human monocytes, cultured for 2 days or more, were treated in vitro with Candida albicans for 24 h, an enhancement of their biosynthesis of the complement components C3 and factor B was found. However, when C. albicans was administered to freshly isolated monocytes, a consistent stimulation of factor B biosynthesis occurred, while the C3 production was increased in about 50% of the donors. C. albicans also induced the release of granulocyte-macrophage colony-stimulating factor (GM-CSF) from the cultured cells, apparently in larger amounts in the donors in whom no stimulation of C3 production was found. An antibody to GM-CSF administered with the yeast at the initiation of the monocyte culture caused an increase in the C3 production. Furthermore, when monocytes were treated with recombinant human GM-CSF either at the same time as or 4 days prior to the addition of C. albicans, the increase in C3 production was suppressed or neutralized, while factor B biosynthesis was unaffected. Taken together, these results indicate that monocytes respond to C. albicans with an increased production of complement factors. This may be an important mechanism both for opsonization of the fungus and for initiation of an inflammatory reaction. At an inflammatory site, this complement response may be suppressed by locally produced GM-CSF.

Effects of human interleukin 3, macrophage and granulocyte-macrophage colony-stimulating factor on monocyte function following autologous bone marrow transplantation

The effects of human interleukin 3 (IL-3), macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were studied on the functional activity of human peripheral blood monocytes from healthy individuals and from eight patients at 4, 8 and 12 weeks following autologous bone marrow transplantation (ABMT). Functions studied included superoxide production, phagocytosis of Candida albicans and reduction of 3-[4,5-dimethylthiazol-2-yl]-2.5-diphenyl tetrazolium bromide (MTT). IL-3 and GM-CSF significantly enhanced the oxidative metabolism of monocytes from healthy individuals, while the effect of M-CSF was moderate. A considerable variability between healthy individuals was found in both resting and cytokine-stimulated monocytes with regard to superoxide production. All three investigated CSFs, i.e. IL-3, M-CSF and GM-CSF did not affect phagocytosis of C. albicans by the cells or their metabolic activity (reduction of MTT). In ABMT patients no deficit in the functional activity of monocytes was found at any time after transplantation and all three CSFs investigated did not modulate the functional activity of the cells. These results suggest that monocytes do not have a major role in infectious complications post-ABMT.

Colony-stimulating factors

Recombinant hematopoietic colony-stimulating factors have profound effects on developing and mature granulocytes, macrophages, and lymphocytes. Use of these agents for treatment of disease may result in a variety of adverse cutaneous reactions. The recent discovery of colony-stimulating factor production by keratinocytes and dermal cells suggests that these agents may also be significant in cutaneous homeostasis and in the pathogenesis of cutaneous diseases.