A regulatory role for tumor necrosis factor (TNF) in ML-1 human myeloblastic leukemia cell maturation

ML-1 human myeloblastic leukemia cells are induced to differentiate to monocytes by conditioned medium (CM) derived from tetradecanoylphorbol acetate (TPA)-treated ML-1 cells. Antibodies to tumor necrosis factor (TNF) inhibited the differentiation-stimulating activity of CM, indicating that this activity is due to the presence of TNF in CM. TNF added to non-conditioned medium was as effective as CM in stimulating ML-1 cell differentiation. In the presence of a low (0.12 ng/ml) concentration of TPA, TNF-induced maturation was synergistically increased and Type I macrophages were formed. With higher (1-10 ng/ml) TPA concentrations, Type II macrophages were also obtained. As the TNF/TPA concentration increased, ML-1 cell differentiation was increasingly inhibited. Mature cells derived from ML-1 cells were found to secrete TNF at concentrations ranging from less than 2 U/ml to greater than 180 U/ml, the amount depending upon the number of cells and the stage of cell maturation. These results indicate that TNF participates in the regulation of precursor cell maturation. Low concentrations of TNF produced by small numbers of mature cells stimulate differentiation, whereas high concentrations of TNF generated by elevated numbers of macrophages inhibit the maturation process, possibly in combination with other cytokines. Because TNF serves as a competence factor for ML-1 cells, (Guan X.-P., Takuma T., Hromchak R. & Bloch A. (1990) Competence and progression in cell differentiation. Proc. Am. Assoc. Cancer Res. 31, 28.), the TNF-induced stimulation of differentiation depends additionally on the action of serum-contained differentiation-specific progression factors.     

Mechanisms of in vivo generation of cytotoxic effector cells against tumor in tumor-bearing mice

Our previous study showed that spleen cells from BALB/c mice bearing RL male 1 lymphoma inhibited the growth of RL male 1 lymphoma by the Winn-type adoptive transfer assay. Although this antitumor activity was mediated by the T-cell subset manifesting the surface phenotype of cytotoxic T-lymphocytes (CTLs), this antitumor activity of spleen cells was not detected by the in vitro cell-mediated cytotoxicity assay (4-h 51Cr release assay). The present study is concerned with the hypothesis that the maturation of the CTLs directed against RL male 1 may be arrested in spleens of the RL male 1-bearing mice and the differentiation into mature CTLs may occur at the tumor site; i.e., the immature CTLs (activated precytotoxic T-cells) may acquire the killing activity when they contact tumor cells at the tumor site. This report shows that BALB/c mice bearing the progressive RL male 1 lymphoma were able to generate CTLs against RL male 1 in the peritoneal cavities when the mice were inoculated i.p. with the irradiated RL male 1 cells. The cytotoxic activity of the peritoneal exudate cells of the RL male 1-bearing mice appeared 3 to 5 days after i.p. inoculation of the irradiated RL male 1 cells and rapidly decreased on day 7 after inoculation. In addition, spleen cells from the RL male 1-bearing mice after i.p. inoculation of the irradiated RL male 1 cells were not cytotoxic, suggesting a highly localized response. The cytotoxic effector cells induced in the peritoneal cavities consisted of T-lymphocytes and natural killer cells. Both cell types were simultaneously induced in the peritoneal cavities of the RL male 1-bearing mice. The T-cell subset mediating cytolytic activity against RL male 1 was shown to consist of Lyt-1+2+ T-cells which were defined by cytolysis with anti-Lyt-1 or anti-Lyt-2 antibody and complement. On the other hand, the normal BALB/c mice inoculated i.p. with the irradiated RL male 1 cells generated natural killer cells in the peritoneal cavities and spleens but the CTLs were not induced. The results from the present and previous studies suggest that precytotoxic or immature cytotoxic T-cells in spleens of the tumor-bearing mice migrate into the circulation and then mature CTLs develop at the tumor site.     

Evaluation of diffuse lung uptake of 201Tl in bronchopulmonary diseases

201Tl scintigraphy was performed in various bronchopulmonary diseases. Applying semiquantitative and visual assessments of grade of 201Tl was observed in various broncho-pulmonary diseases with multiple or numerous abnormal shadows in the lung fields, and obvious lung uptake was also shown even in some cases with few or no abnormal shadows. Positive results of moderate and marked lung uptake of 201Tl more than 60.0% were obtained in diffuse interstitial pneumonia, hypersensitivity pneumonitis, silicosis, the disseminated type of pulmonary tuberculosis and primary lung cancer. The ratio of radioactivity of the lung (maximum) to the upper mediastinum was 1.04 +/- 0.24 in healthy controls, and more than 2.0 in diffuse interstitial pneumonia, hypersensitivity pneumonitis and silicosis. The ratio of radioactivity of the right lung to the administered dose of 201Tl was 1.5 +/- 0.9% in healthy controls, and more than 3.0% in diffuse interstitial pneumonia, silicosis, the disseminated type of pulmonary tuberculosis and primary lung cancer. Lung uptake of 201Tl was diffuse, homogeneous and marked in diffuse interstitial pneumonia and hypersensitivity pneumonitis, while it was scattered and slight in chronic obstructive lung diseases. 201Tl scintigraphy seems to be useful for detecting interstitial disorders of the lung including edema, inflammatory and granulomatous changes, especially in cases with slightly abnormal or normal chest X-ray films.     

A Case of I-Cell Disease

A case of I-cell disease is reported. The patient suffered from several episodes of pneumonia, and died of pneumonia at 12 months of age. Tissue specimens obtained at autopsy were stained with colloidal iron to demonstrate acid mucopolysaccharides. Characteristic foamy changes were observed in organs such as the heart, kidneys, liver, spleen and brain. An interesting finding in this case was that not only the interstitial cells but the alveolar epithelium in the lung showed the same foamy changes. The major causes of death of patients with I-cell disease are congestive heart failure and recurrent respiratory infections. However, there have been few reports on the histological changes in the lungs, and none have described the changes in the alveolar epithelium. Further cases must be investigated to examine the pathological relation between the histological changes in the lungs and the cause of death, because recurrent respiratory infections are the major contributor to death in patients with I-cell disease.     

Survival period of tumor-bearing mice is prolonged after the interferon-gamma-producing gene transfer

A highly tumorigenic keratinocyte-derived carcinoma cell line, designated as Pam-T, was established from a Pam212 line. The intradermal injection of more than 10(5) of these cells into syngeneic BALB/c mice induced substantial tumors. The tumors progressively enlarged and then invaded the peritoneal cavity leading to the death of the host mice. To comprehensively investigate the effects of interferon-gamma on tumorigenicity, we manufactured interferon-gamma-producing PamT cells by interferon-gamma gene transfer and examined the characteristics of the tumors induced by these cells in syngeneic mice. Interferon-gamma producing cells exhibited an apparently similar in vitro cell growth pattern and in vivo tumor formation to control cells, but the mean survival of the mice with the interferon-gamma-producing cells was significantly longer compared with control mice.