Rat basophilic leukemia cells stiffen when they secrete

RBL cells provide a useful model of the IgE and antigen-dependent stimulus-secretion coupling of mast cells and basophils. We have measured cellular deformability to investigate the participation of cytoskeletal mechanical changes. Cross-linking cell-surface IgE-receptor complexes with multivalent ligands not only triggered secretion but also caused the cells to stiffen, i.e., to become more resistant to deformation. This mechanical response required receptor cross-linking, had a time course similar to that of secretion, and was reversed by DNP-L-lysine, a competitive inhibitor of antigen binding. Hence the same stimulus seems to elicit both stiffening and secretion. Cytochalasin D, which inhibits actin filament assembly, prevented or reversed stiffening, thereby implicating the cytoskeleton in the mechanical response. Increasing intracellular calcium ion concentration with the ionophore A23187 stiffened cells and stimulated secretion. Activation of protein kinase C with a phorbol ester also stiffened cells and enhanced both the stiffening and secretion caused by the ionophore. Yet cytochalasin D enhances secretion whereas activation of protein kinase c alone is insufficient for secretion. Therefore stiffening is neither necessary nor sufficient for secretion. These results characterize a cytoskeletal mechanical response triggered by the same receptor-dependent stimulus that elicits secretion and by second messengers that are thought to mediate between the receptor signal and secretion. The function of the mechanical response, however, remains to be determined.

[Establishment of human glioma cell line--nude mice solid tumor model NHG-1 and its characteristics]

Establishment and its characteristics of a nude mice solid tumor model NHG-1 from human glioma cell line are reported. 5-8 week old NC nude mice of both sexes and SHG-44 cell line used in this experiment were from our laboratory. The initial successful transplantation rate was 7/11 (64%) and that of 30 passages in the subsequent 4 years was 100%. After subcutaneous inoculation, growth curve showed a latent period in week 1-2, slow growing period in week 3-4, rapid growing period in week 5-6 and a final plateau period in week 7. The doubling time was 7 days and cell cycle time was 2.5 days. The cells in G1, S and G2M phases comprised 56%, 27% and 17%, respectively. The survival time of the host was 54 +/- 15 days. The tumor tissues showed a tendency towards invading the surrounding soft tissues. By morphological observation with light and electron microscopes, LDH isozyme assay, PAP immuno-histochemistry labelling GFAP and chromosome analysis, it is confirmed that the transplantable tumor possesses the characteristics of human malignant glioma. The estrogen receptor in the transplantable tumors demonstrated by cytochemical assay indicates that the glioma carcinogenesis is related to endocrine factor of the host. The therapeutic effects of anticancer drugs, such as ACNU, BCNU and 10-hydroxy-2-decenoic acid from the royal jelly on NHG-1 model are evaluated.

Pulmonary surfactant activity after severe steam inhalation injury in rabbits

Lung water content, Pao2, surface tension (in terms of hysteresis) and lecithin content of both bronchial irrigation fluid and lung homogenates were determined after severe steam inhalation injury in rabbits. At the time of a decrease in Pao2 and an increase in lung water content there was a moderate fall in pulmonary surfactant activity; as shown by a progressive decrease in the area of the hysteresis loop and a decrease of the lecithin content in both bronchial irrigation fluid and lung homogenate. It is proposed that a fall in pulmonary surfactant activity plays an important role in the pathogenesis of pulmonary oedema after inhalation injury. Successive determinations of lecithin content and/or surface tension of bronchial irrigation fluid are recommended as early diagnostic and prognostic aids in severe inhalation injury.

Lateral electromigration and diffusion of Fc epsilon receptors on rat basophilic leukemia cells: effects of IgE binding

We have used in situ electromigration and post-field relaxation (Poo, M.-m., 1981, Annu. Rev. Biophys. Bioeng., 10:245-276) to assess the effect of immunoglobulin E (IgE) binding on the lateral mobility of IgE-Fc receptors in the plasmalemma of rat basophilic leukemia (RBL) cells. Bound IgE sharply increased the receptor's electrokinetic mobility, whereas removal of cell surface neuraminic acids cut it to near zero. In contrast, we found only a small difference between the lateral diffusion coefficients (D) of vacant and IgE-occupied Fc receptors (D: 4 vs. 3 X 10(-10) cm2/s at 24 degrees C). This is true for monomeric rat IgE; with mouse IgE, the difference in apparent diffusion rates was slightly greater (D: 4.5 vs. 2.3 X 10(-10) cm2/s at 24 degrees C). This range of D values is close to that found in previous photobleaching studies of the IgE-Fc epsilon receptor complex in RBL cells and rat mast cells. Moreover, enzymatic depletion of cell coat components did not measurably alter the diffusion rate of IgE-occupied receptors. Thus, binding of fluorescent macromolecular probes to cell surface proteins need not severely impede lateral diffusion of the probed species. If the glycocalyx of RBL cells does limit lateral diffusion of the Fc epsilon receptor, it must act primarily on the receptor itself, rather than on receptor-bound IgE.