Granulocyte macrophage colony-stimulating factor and interleukin 4 enhance the number and antigen-presenting activity of circulating CD14+ and CD83+ cells in cancer patients.

Antigen-presenting cells (APCs) are essential for stimulating antigen-specific immunity, including immunity against tumor cells. We hypothesized that systemic administration of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, which promote monocytes to differentiate into dendritic cells in vitro, might enhance the number and antigen-presenting activity of CD14+ cells in vivo. Patients with metastatic solid malignancies were treated with daily s.c. injections of either GM-CSF alone (2.5 microg/kg/day) or GM-CSF in combination with IL-4 (0.5-6.0 microg/kg/day) in a multicohort study. When given alone, GM-CSF increased the number of CD14+ cells but did not enhance the cells' expression of APC markers or antigen-presenting activity. In contrast, combination therapy with GM-CSF and IL-4 stimulated CD14+ cells to acquire several APC characteristics including increased expression of HLA-DR and CD11c, decreased CD14, increased endocytotic activity, and the ability to stimulate T cells in a mixed leukocyte reaction. Combination therapy also induced a dose-dependent increase in the number of CD14-/CD83+ cells with APC activity. Clinically significant and sustained tumor regression was observed in one patient. Systemic therapy with GM-CSF and IL-4 may provide a mechanism for increasing the number and function of APCs in patients with cancer.

Interferon-alpha and granulocyte-macrophage colony-stimulating factor differentiate peripheral blood monocytes into potent antigen-presenting cells.

The diverse roles of interferon-alpha (IFN-alpha) in regulating the immune response to infectious agents suggested that it might affect dendritic cell (DC) development. Peripheral blood mononuclear cells cultured with IFN-alpha and granulocyte-macrophage colony-stimulating factor (GM-CSF) developed a dendritic morphology and expressed high levels of the class I and II human leukocyte antigens (HLA), B7 co-stimulatory molecules, adhesion proteins, and CD40. Elevated DC expression of B7-2 and HLA-DR was observed with increasing IFN-alpha concentrations up to 5000 U/mL. The effects of IFN-alpha on DC immunophenotype were not reversed by adding neutralizing antibodies against interleukin-4 (IL-4) or tumor necrosis factor alpha to the cell cultures or by eliminating lymphocytes from the cultures. The addition of IFN-alpha to cultures containing optimal concentrations of IL-4 and GM-CSF significantly increased the B7-2 and HLA-DR levels above those present on DCs grown in two cytokines. The DCs generated with IFN-alpha and GM-CSF were potent antigen-presenting cells in allogeneic mixed leukocyte reactions. They also were capable of taking up, processing, and presenting tetanus toxin to autologous T lymphocytes. These results demonstrate an important role for IFN-alpha in the generation of DCs with potent antigen-presenting capabilities from peripheral blood monocytes.

Efficient transduction of early passage human melanoma to secrete IL-4.

Augmentation of tumor immunogenicity has been increasingly studied as a strategy to develop host immunity against established malignancies. Genetic modification of tumors to secrete immunoregulatory peptides such as IL-4 has been demonstrated to augment tumor immunogenicity and enhance the induction of tumor reactive lymphoid cells in animal models. To explore the ability of IL-4 to augment the immunogenicity of melanoma cells, we constructed a recombinant retrovirus vector encoding for human IL-4 and used it to transduce human melanomas. After optimizing retrovirus transduction conditions using a reporter virus, an IL-4 encoding retrovirus vector was used to transduce early and late passage melanoma cells. IL-4 production rates of up to 2000 pg/ml per 24 h per 10(6) cells were achieved, and provirus could be detected by Southern blot of the transduced cells at 0.1 copies per cell. The IL-4 produced by the melanoma cells was biologically active. Irradiated transduced melanoma cells continued to produce IL-4 for at least two weeks of observation. Thus melanoma cells can be efficiently modified to secrete biologically active IL-4, and may be suitable substrates for autologous tumor cell vaccines.

Marijuana and cocaine impair alveolar macrophage function and cytokine production.

Use of marijuana and cocaine is on the rise in the United States. Although pulmonary toxicity from these drugs has occasionally been reported, little is known about their effects on the lung microenvironment. We evaluated the function of alveolar macrophages (AMs) recovered from the lungs of nonsmokers and habitual smokers of either tobacco, marijuana, or crack cocaine. AMs recovered from marijuana smokers were deficient in their ability to phagocytose Staphylococcus aureus (p < 0.01). AMs from marijuana smokers and from cocaine users were also severely limited in their ability to kill both bacteria and tumor cells (p < 0.01). Studies using NG-monomethyl-L-arginine monoacetate, an inhibitor of nitric oxide synthase, suggest that AMs from nonsmokers and tobacco smokers were able to use nitric oxide as an antibacterial effector molecule, while AMs from smokers of marijuana and cocaine were not. Finally, AMs from marijuana smokers, but not from smokers of tobacco or cocaine, produced less than normal amounts of tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-6 when stimulated in culture with lipopolysaccharide. In contrast, the production of transforming growth factor-beta, an immunosuppressive cytokine, was similar in all groups. These findings indicate that habitual exposure of the lung to either marijuana or cocaine impairs the function and/or cytokine production of AMs. The ultimate outcome of these effects may be an enhanced susceptibility to infectious disease, cancer, and AIDS.