Interleukin-2 (IL-2) has a key role in the antigen-specific clonal growth of T lymphocytes, by virtue of its interaction with a specific cell-surface receptor (IL-2R). The growth signal seems to be delivered by IL-2 bound to the high-affinity, but not the low-affinity, receptor. Genes encoding IL-2 and its receptor (that is, Tac-antigen) have been cloned and analysed in detail. We have now achieved cell-type-specific reconstitution of the high-affinity human IL-2R by expressing the complementary DNA cloned from normal lymphocytes. A mouse T-lymphocytic line, EL-4, expressed human IL-2R with high (dissociation constant (Kd) = 160-220 pM) and low (Kd = 2.1-2.2 nM) affinity for recombinant human IL-2, while mouse L929 cells expressed only a single class of the IL-2R with lower affinity (Kd = 34.5 nM) for the ligand. We also show that the human IL-2R expressed in EL-4 cells responds to IL-2 and mediates reversed signal transduction: growth of the EL-4 cells harbouring the IL-2R is inhibited specifically by human recombinant IL-2. The approach described here may provide a general experimental framework for elucidating the molecular basis of signal transduction mediated by specific receptor-ligand interaction.

Animals↗

PubMedDate not supplied

Interferon-gamma induces retinoic acid-inducible gene-I in endothelial cells.

Interferon-gamma (IFN-gamma) induces expression of multiple genes in endothelial cells. Retinoic acid-inducible gene-I (RIG-I) encodes a protein belonging to the DExH-box family, but details of its physiological function are not clear. RIG-I is induced in leukemia cells by retinoic acid and in endothelial cells by lipopolysaccharide. In the present study, the authors found that IFN-gamma also induces the expression of RIG-I in human umbilical vein endothelial cells. Induction of RIG-I mRNA by IFN-gamma was not altered by the treatment with cycloheximide or interleukin-4. Fluorescent immunostaining and Western blot analysis revealed cytoplasmic distribution of RIG-I. The in situ endothelium in a normal lung tissue was also found to express RIG-I protein. Although the physiological function of RIG-I is still unknown, induction of RIG-I by IFN-gamma may play an important role in inflammatory or immunological reactions in endothelial cells.

Cell Line↗

PubMedDate not supplied

Double-stranded RNA induces the synthesis of retinoic acid-inducible gene-I in vascular endothelial cells.

Viral infection induces various responses in vascular endothelial cells. Polyinosinic-polycytidylic acid (poly IC) is a synthetic double-stranded RNA (dsRNA), and treatment of cells with poly IC mimics the viral infection to the cells. Retinoic acid-inducible gene-I (RIG-I) is a protein belonging to the DExH-box family and designated as a putative RNA helicase. RIG-I is considered to play a role in antiviral responses through the regulation of gene expressions. In the present study, the authors treated human umbilical vein endothelial cells (HUVECs) with poly IC and found that poly IC induced the expression of RIG-I. The poly IC-induced RIG-I expression was inhibited by the preincubation of the cells with 2-aminopurine, an inhibitor of dsRNA-dependent protein kinase (PKR). Immunohistochemical examination revealed high levels of RIG-I immunoreactivity in vascular endothelial cells in the thalamus from rats inoculated with hantavirus. Induction of RIG-I by poly IC may be involved in the antiviral responses in endothelial cells.

Animals↗

PubMedDate not supplied

Construction of a laser transmission photo-scanner: pre-clinical investigation (report 2).

A prototype high-speed laser transmission photo-scanner using a 1 mm He-Ne laser beam and corresponding detector was constructed. Signals obtained from the detector were digitalized and stored in floppy disks by a micro-computer and displayed as color-coded pictures on the CRT monitor. The data were analyzed and absorption in the tissue was shown in a histogram. Breast tissue was simulated using pork, ham, lard, and cheese in a pre-clinical investigation. Normal breasts of volunteers were also examined. When disks of varying sizes were inserted into ham and cheese of various thicknesses, it was found that disks closer to the beam's point of entrance produced the best images, while disks in the center and those closer to the exit were poorly detected. Disks close to the surface were better detected than central lesions. Laser transmission images of normal breasts of twelve volunteers were symmetrical but often nonhomogeneous because of the complexity of breast tissue.

Breast↗

PubMedDate not supplied

Usefulness of direct coronal CT in the diagnosis of urinary bladder tumor.

Direct coronal CT was performed on 6 cases of urinary bladder tumor in which conventional axial transverse CT failed to depict the relationship between the lesion and bladder wall. GE CT/T 8800 was used, and the bladder was scanned with patients crouched on the table opposite the gantry. The relationship between the tumor and bladder wall as well as the surrounding organs was visualized in 5 of 6 cases examined. THe CT diagnosis and histological findings coincided in 4 of these 5. Direct coronal CT was useful for diagnostic determination of clinical stage for tumors occurring in the apical or basal region of the urinary bladder.

Humans↗