Effects of macrophage colony-stimulating factor and interleukin-2 administration on NK1.1(+) cells in mice.

We studied the effects of M-CSF and IL-2 on NK1.1(+) cell activity in vivo and in vitro. Administration of M-CSF increased the number of splenic NK1.1(+) cells (vs. saline: P<0.01). Moreover, the combination of M-CSF and IL-2 (M-CSF+IL-2) produced a synergistic expansion of the number of NK1.1(+) cells compared with each single treatment (vs. saline: P<0.001). The NK1.1(+) cells were isolated from the spleen of each treated mouse (four treatment groups: saline, IL-2 alone, M-CSF alone, M-CSF+IL-2) and their functions (IL-2-induced proliferation, IFN-gamma production and cytostatic activity) were evaluated in vitro. The NK1.1(+) cells from M-CSF alone and M-CSF+IL-2 treated mice showed greater responsiveness in terms of IL-2-induced proliferation, production of IFN-gamma and cytostatic activity than the cells from saline and IL-2 alone treated mice. The NK activity in vivo was enhanced by the administration of M-CSF and IL-2, as assessed by the 'Lung clearance assay' (clearance of Yac-1 cells in lung). And the M-CSF+IL-2 treatment induced the highest NK activity of the four treatments. To show a practical effect of upregulation of NK activity in vivo by M-CSF and IL-2 administration, the effect of the four treatments on an experimental tumor metastasis model was examined. The IL-2 alone, M-CSF alone and M-CSF+IL-2 treatment reduced the metastasis of B16 melanoma. And the M-CSF+IL-2 treatment proved of greater benefit to the antimetastatic activity than each single treatment. Our results demonstrated that the administration of M-CSF increases the number of NK1.1(+) cells, which have good responsiveness to IL-2. Furthermore, the combination treatment of M-CSF and IL-2 in vivo augments the increase of NK1.1(+) cells. And these effects can contribute to the antimetastatic activity in vivo.

Effects of macrophage-colony-stimulating factor on cyclophosphamide-injected mouse NK1.1+ cell activity.

We injected cyclophosphamide into mice and examined their natural killer (NK) activity both in vitro and in vivo. Cyclophosphamide injection temporarily abrogated the lung clearance activity of Yac-1 lymphoma cells, which is considered to be an index of NK activity in vivo. However, administration of recombinant human macrophage-colony-stimulating-factor (rhM-CSF) to cyclophosphamide-injected mice restored the lung clearance activity. To clarify whether the administration of rhM-CSF activated NK cells, we purified NK1.1+ cells from mice treated with cyclophosphamide and/or rhM-CSF and examined their functions (cytotoxicity, proliferation, and interferon gamma production) in vitro. Cyclophosphamide injection decreased the number, but did not suppress the functions of NK1.1+ cells. The numbers of NK1.1+ cells in cyclophosphamide-injected mice restored by rhM-CSF administration. And the functions of NK1.1+ cells from both saline-injected and cyclophosphamide-injected mice were accelerated by rhM-CSF administration. These results suggested that the temporary abrogation of NK activity in vivo caused by cyclophosphamide injection was due to a decrease in the number and not to suppression of the functions of NK1.1+ cells. The injection of cyclophosphamide into mice increased the number of tumor (B16 melanoma) nodules formed in the lungs and liver. However, treatment with rhM-CSF recovered the anti-metastatic activity in the lungs of cyclophosphamide-injected mice. These results show that administration of rhM-CSF restores NK activity suppressed by cyclophosphamide injection in vivo.

In vivo stimulatory effect of macrophage colony-stimulating factor on the number of stroma-initiating cells.

The in vivo effect of human macrophage colony-stimulating factor (M-CSF) on the number of cells that formed stromal colonies in an in vitro culture system (stroma-initiating cells; SICs) was investigated. We found that the number of SICs in the femurs of C57BL/6 mice was significantly increased by the treatment with M-CSF. We also found that the SICs were resistant to at least three different chemotherapeutic reagents, 5-fluorouracil (5-FU), cytarabine, and cyclophosphamide, because the femoral cells of mice treated with these reagents contained higher numbers of SICs than those of untreated mice. M-CSF treatment also increased the number of SICs of the reagent-pretreated mice. The SICs detected in our culture system were present only in Mac-1(-)CD45(-) cells, and the M-CSF treatment of 5-FU-pretreated mice actually increased the number of Mac-1(-)CD45(-) SICs. The Mac-1(-)CD45(-) SICs collected from mice that were pretreated with 5-FU and then treated with M-CSF formed stromal colonies under in vitro culture conditions that did not contain M-CSF but did contain a high concentration of fetal calf serum. This result suggested that SICs collected following the treatment procedure did not necessarily require the presence of M-CSF for their in vitro proliferation. Our study indicated that M-CSF has the ability to increase the number of progenitor or precursor cells for bone marrow stromal cells in vivo system.

Characterisation of a catabolic epoxide hydrolase from a Corynebacterium sp.

The epoxide hydrolase (EH) from Corynebacterium sp. C12, which grows on cyclohexene oxide as sole carbon source, has been purified to homogeneity in two steps, involving anion exchange followed by hydrophobic-interaction chromatography. The purified enzyme is multimeric (probably tetrameric) with a subunit size of 32,140 Da. The gene encoding Corynebacterium EH was located on a 3.5-kb BamHI fragment of C12 chromosomal DNA using a DNA probe generated by PCR using degenerate primers based on the N-terminal and an internal amino acid sequence. Sequencing and database comparison of the predicted amino acid sequence of Corynebacterium EH shows that it is similar to mammalian and plant soluble EH, and the recently published sequence of epichlorohydrin EH from Agrobacterium radiobacter AD1 [Rink, R., Fennema, M., Smids, M., Dehmel, U. & Janssen, D. B. (1997) J. Biol. Chem. 272, 14650- 14657), particularly around the catalytic site. All of these proteins belong to the alpha/beta-hydrolase-fold family of enzymes. Similarity to the mammalian microsomal EH is weaker.