Respiratory tract, mucosal immune

There was an increased incidence of a mycoplasma respiratory tract infection in rats exposed to 260 ppm hexachloroethane for 6 weeks but not in rats exposed to lower doses or in other species. This could indicate compromised immune function or a weakened mucosal barrier along the respiratory epithelium. There were no studies identified that evaluated a wide range of immunological parameters. Therefore, there are no reliable LOAELs or NOAELs for this end point. Increases in spleen weights are not classified as LOAELs since they were not accompanied by histopathological changes. 

This chapter first provides a description of immunity in general and then more specifically, immunity in the mucosal immune system. The immune response of both intestinal and respiratory tracts will be described in detail as these are the two most common portals of targeted vaccine development for mucosal immunity. The chapter will cover the basis of mucosal immunity using plant-based oral vaccines. Strategies for increasing mucosal immunity, such as the use of adjuvants, will also be discussed. Finally, the chapter will cover the precliiucal tests and various cliiucal trials that are taking place with respect to production of human and veterinary therapeutic proteins in plants. 

Nevertheless, there is also accumulating evidence that a certain regionalization exists in the mucosal immune system, in particular a dichotomy between the gut and the upper respiratory tract. Differences in the antigenic repertoire, adhesion molecules or chemokines involved in leukocyte extravasation might explain this disparity. Primed immune cells may tend to home to the effector sites corresponding to the inductive sites, where the initial antigen contact took place. Such regionalization within the common mucosal immune system has to be taken into account in the development of certain mucosal vaccines [11]. 

However, the nasal epithelium has little ability to break down drugs. The extensive mucosal surface of the nose has a lining of pseudostratified epithelium as well as cilia and the goblet cells involved in the secretion of mucus. The lymphoid tissue primarily involved in the mucosal immune responses is the mucosal-associated lymphoid tissue (MALT). The different regions of the respiratory tract that play an influencing role in the immune system are as follows ... 

Parenteral Route. Parenteral vaccination remains the immunization method of choice for most antigens because it provides more effective immune response than do any other routes of vaccination in most cases. Every years millions of people receive inactivated influenza vaccine by parenteral administration. Subcutaneous vaccination with inactivated influenza vaccine is known to induce simultaneous immune responses in the blood and upper respiratory tract of subjects. The immune response, i.e., the increase in the number of influenza virus-specific antibody-secreting cells in peripheral blood and tonsils, increased rapidly to reach a peak within 1 week after vaccination.Parenteral vaccination of a DNA vaccine encoding glycoprotein D of herpes simplex virus type 2 resulted in systemic cellular and humoral responses. The mucosal humoral responses generated by intramuscular and intradermal vaccination were comparable with those obtained by mucosal vaccination. The DNA vaccine was able to... 

Fig. 4 Mucosal immunization and production of IgA antibodies in various mucosal surfaces via the common mucosal-simmu-nization system. Nasal and rectal vaccinations usually result in IgA production in upper respiratory tract and genitourinary tract, respectively, whereas effector sites by oral vaccination are expected to include many mucosal surfaces.

Metal fume fever, a critical end point, was observed in workers who inhaled high levels of zinc oxide fumes or dust. The mechanism of metal fume fever has been reported to be an immune response to zinc oxide in the respiratory tract. The anemia observed in humans and animals after oral exposure to high levels of zinc could result from a zinc-induced copper deficiency. Excess levels of dietary zinc inhibit the transport of copper to the blood from either the intestinal lumen or the intestinal mucosal cell. 

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