Effects of epithelium on the mechanism of mediator release from guinea pig tracheal tissues sensitized by IgG1 versus IgE antibody

In the present work, we have examined the effect of PAF, removal of epithelium, the mechanism of desensitization, and the substances that increases the level of intracellular c-AMP on the differences of mediator release from superfused tracheal strips after passive sensitization with IgG1 versus IgE Ab. In the passive sensitized tracheal tissues, the effect of PAF and the mechanism of desensitization have been examined by PAF antagonist, CV 3988 and DFP, respectively. The epithelium was stripped from one-half of each trachea by mechanical means. Both superfused tracheal tissues were challenged with Ox-Ag. Inhibitors of mediator release were added into a superfused buffer. Hist released was determined by spectrophotofluorometer, and LT by radioimmunoassay. PAF known to mediate the allergic reaction was not released by Ag after both Ab sensitization. Epithelium removal resulted in similar contraction, Hist and LT release after IgG1 Ab activation, but in the IgE Ab activation, epithelium removal resulted in smaller contraction and Hist release. In the L-cysteine and indomethacin pretreatment after two Ab sensitization, epithelium removal decreased the release of Hist and LT. The compound 48/80 pre-challenge and epithelium removal resulted in the increase of Hist release, but in the decrease of LT release after IgG1 or IgE sensitization. The Amount of LT released by Ag after compound 48/80 pre-challenge increased in the absence or presence of epithelium after both Ab sensitization. Mediator release from tissues sensitized with both Abs was not changed by DFP. The responses of inhibitors to prevent the mediator release were more effective on the IgE Ab than on the IgG1 Ab sensitization. These studies suggest that the tracheal epithelium can act to inhibit immune- and non-immune-induced airway responses. Non-immunological responses may in part reflect the role of epithelium as a diffusion barrier and modulator of mediator release. These data also suggest that immunological responses are related to the localization and functional heterogeneity of tissue mast cells.

Intravenous immunoglobulin for prophylaxis of neoneatal sepsis in the premature infants

Newborn premature babies have lwo levels of transplacentally acquired maternal immunoglobulin which is mostly transferred after 32~34 weeks gestaton, therefore they may have IgG deficiencies that increase their susceptibility to bacterial infection. We performed this study to determine whether intravenous immunoglobulin (IVIG) therapy improves mortality or infection occurrance rate. From 1 october 1991 to 31 July 1992, 73premature newborn infants with gestational age< or =34weeks were enrolled: the theatment group, consisting of 43infants who received prophylactic intravenous immunoglobulin therapy (500mg/kg/week) and the control group, consisting of 30infants who did not receive. prophylactic intravenous administration of immunoglobulin to preterm infants with a gestational ageage< or =34week, at a dose of 500mg/kg/week, results in maintenance of a satisfactory serum IgG level throughout the high-risk period for infection. But the incidence rates of proven or very probable sepsis, mortality for sepsis and total mortality in the infants receiving intravenous immunoglobulin were not significant differences when compared with those in the control infants. No adverse effects were noted after immunoglobulin transfusions in our subjects. In conclusion, our study does not show any decrease in bacterial infection rate or in mortality rate, and no study in the literature has shown absolute proof of the prophylactic efficacy of IVIG in premature newborns. Larger studies are necessary to confirm these observations and to determine more effective dosing schedules and the optimal levels of orhanism-spectific antibodies. And specific hyperimmnue of monoclonal antibody preparations may be required to provide reliable sources of effective prophylactic to premature neonate with high risk in bacterial sepsis.