Immunity, concept

Dmg receptors are chemical entities which are typically, but not exclusively, small molecules that interact with cellular components, frequently at the plasma membrane level (1,2). There are many types of receptors heat, light, immune, hormone, ion channel, toxin, and vims are but a few that can excite a cell. The receptor concept can be appHed generally to signal recognition processes where a chemical or physical signal is recognized. This recognition is translated into response (Fig. 3) and the process can be seen as a flow of information. 

It should be noted that Fig. 1.15 (top) is based entirely on thermodynamic data and is therefore correctly described as an equilibrium diagram, since it shows the phases (nature and activity) that exist at equilibrium. However, the concepts implicit in the terms corrosion, immunity and passivity lie outside the realm of thermodynamics, and, for example, passivity involves both thermodynamic and kinetic concepts it follows that Fig. 1.15 (bottom) cannot be regarded as a true equilibrium diagram, although it is based on one that has been constructed entirely from thermodynamic data. 

Although important contributions in the use of electrical measurements in testing have been made by numerous workers it is appropriate here to refer to the work of Stern and his co-workerswho have developed the important concept of linear polarisation, which led to a rapid electrochemical method for determining corrosion rates, both in the laboratory and in plant. Pourbaix and his co-workers on the basis of a purely thermodynamic approach to corrosion constructed potential-pH diagrams for the majority of metal-HjO systems, and by means of a combined thermodynamic and kinetic approach developed a method of predicting the conditions under which a metal will (a) corrode uniformly, (b) pit, (c) passivate or (d) remain immune. Laboratory tests for crevice corrosion and pitting, in which electrochemical measurements are used, are discussed later. 

Although a humoral immune response is the primaiy protection against most viral and some bacterial diseases, protective defense against other pathogens such as HIV, Plasmodium and Mycobacterium tuberculosis requires a cytotoxic response mediated by CD8+ T-cells (CTL response). Since the introduction of the vaccination concept by Jenner almost 200 yeats ago, only few vaccines have been developed that are able to induce a CTL response. These vaccines are usually attenuated live vaccines that are accompanied by certain risks and are not readily available for most pathogens. The immense appeal of DNA vaccines can be attributed to a considerable part to the fact that they are able to induce... 

The Th-1 /Th-2 paradigma forms a core mechanism regulating the nature of an immune response. More recently, this concept was further developed by identifying Th-subsets with predominantly suppressing properties, T-regulatory cells (Treg). These cells also play a major role in keeping those cells at rest, which have escaped central tolerance (peripheral self tolerance). 

Contrary to other elicitors of non-immune anaphylactic reactions (radiocontrast media, neuromuscular blocking agents, non-steroidal anti-inflammatory drugs (NSAIDs)) where there are at least hypothetical concepts regarding the pathomecha-nism of these reactions via increased mediator release (e.g. histamine release, shift in arachidonic acid metabolism from prostaglandins towards leukotrienes, etc.) [26], there is almost no literature regarding the pathomechanism of these reactions after LA application. 

A recent series of experiments which may be related to this concept has been reported by Prehn and Lawler (29) They treated 10 strains of mice with two different dose levels (5% and 0.05%) of 3-methylcholanthrene and observed that the rank order of susceptibility, as measured by the average number of tumor-free days, was reversed on going from the higher to the lower dose. They suggested differential stimulation of immune response as an explanation of their results but it is also possible that different dose-responses, as suggested by Druckrey s equation (equation 5), may be important. 

The seminal work by early transplant researchers eventually led to the concept of histocompatibility.1,2 Histocompatibility describes the process where polymorphic genes encode cell membrane antigens that serve as targets for immune response, even within a species. Further research in transplant immunobiology has led to an accurate understanding of the immune response after transplantation.1,2... 

Often the terms vaccination and immunization are used interchangeably even though they are very distinct concepts. Vaccination refers to the act of administering a vaccine, while immunization refers to the development of immunity to a pathogen. The delivery of a vaccine does not imply that the individual mounted an adequate immune response to the vaccine to elicit protection. However, immunization implies that the act of vaccination resulted in the development of protective immunity. 

Kohl KS, Marcy SM, Blum M, et al. Fever after immunization current concepts and improved future scientific understanding. Clin Infect Dis 2004 39 389-394. MacKay IR, Rosen FS. Vaccines and vaccination. N Engl J Med 2001 345 1042-1053. Moylett EH, Hanson IC. Mechanistic actions of the risks and adverse events associated with vaccine administration. J Allergy Clin Immunol 2004 114 1010-1020. Rhee P, Nunley MK, Demetriades D, et al. Tetanus and trauma a review and recommendations. J Trauma 2005 58 1082-1088. Weber DJ, Rutala WA. Immunization of immunocompromised persons. Immunol Allergy Clin North Am 2003 23 605-634. 

Reding R, Davies HF. Revisiting liver transplant immunology from the concept of immune engagement to the dualistic pathway paradigm. Liver Transpl 2004 10 1081-1086. 

The concept of de-PEGylation can be applied to the development of nanoparticle-based drug delivery systems. PEG is used for the modification of liposomes to increase their blood circulation time [38], However, it also prevents cellular uptake, resulting in a decrease in therapeutic efficiency thus, modifications of the liposome surface with PEG interfere with membrane fusion to the cell membrane and liposome decomposition [39]. One of the possible strategies to solve this problem is to cleave the PEG chains after the nanoparticle reaches the target site (Fig. 9). This system of de-PEGylation of liposomes is also useful in avoiding the immune... 

The presence of tumour-specific antigens implies that the immune system should be capable of recognizing and destroying transformed cells. This concept, known as immunosurveillance, probably does function to some extent in the body. The immune system does respond to the presence of some tumours, causing their partial or complete regression. The major anti-tumour immune elements include ... 

McGhee, J.R. et al., The Mucosal Immune System from Fundamental Concepts to Vaccine Development, Vaccine. 10, 75, 1992. 

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