Immunogenic reactions

In addition to the pivotal studies, several publications (Table 6.2) used other methods to test the response of individuals with celiac disease who were introduced to oats. These studies did not fulfill the selection criteria of pivotal studies namely an in vivo oats challenge with an intestinal/skin biopsy to assess the biological response to the introduction of oats into an otherwise gluten-free diet. Instead, they used various in vitro techniques to assess the immune response to avenin, or serology without an intestinal mucosal biopsy. Most of the methods used duodenal mucosal cultures prepared from biopsies or intestinal T cell lines obtained from individuals with celiac disease. Other studies measured the immunogenic reaction in peripheral lymphocytes or measured the presence of various antibodies in individuals with verified celiac disease who included oats in their diet, in comparison with a reference group (Table 6.2). Some of these studies used patients that were previously included in pivotal studies. These studies are identified with an asterisk ( ) in Table 6.2. 

Maintaining the sterility of biopharmaceutical products is especially important due to the relative potency and their innate potential for immunogenic reactions. Further, the biochemical nature of these compounds enables them to serve as potential nutrients for invading organisms. Methods for sterilizing small molecules include... 

The propensity of polypeptide and protein drugs to form reversible and irreversible aggregates in solution is of great concern as it may lead to the loss of desired pharmacological activity, immunogenic reactions, and unacceptable physical appearance in long-term therapeutic system. To overcome these drawbacks, several approaches have been proposed, including the use of amphiphatic excipients, chemical modification, and site-directed mutation [104]. 

When the dot blot technique is used, as much as 1 mg of protein is placed in each well dot, and the total protein is tested for a visible immunogenic reaction. No visible dot means that the impurities are less than 5ppb. Lanes 1,4,6, and 8, contain Model Proteins A, A, B, and respectively. In Lanes 1,4,6, and 8, the top two dots contain Img, whereas the bottom two dots contain 0.1 mg thus the effect of a 10-fold dilution can be seen. Lanes 2 and 10 are the negative and the positive controls, respectively, showing the experiment to be working well. On further purification of Model Proteins A, A, B, and x, as shown in lanes 3,5,7, and 9, respectively, no spot can be detected. This means that purification of the model proteins has been obtained to the level where impurities detectable by the Western immunodotblot technique are less than 5 ppb. 

Although unlike RIA, enzyme immunoassays can be carried out in homogeneous systems without a separation step (based on the change in enzyme activity during the immune reaction), in practice, heterogeneous (enzyme-linked immunosorbent assay) methods are much more frequently used. The antibody, or in the case of the double-antibody method the second antibody, is immobilized, either covalently or by coating enzyme multiplied immunoassay technique (EMIT). This can be done on the walls of microtiter plates. After the immunogenic reaction, the enzyme activity, which is the equivalent of radioactivity in RIA systems, can be measured by suitable photometric methods on the microtiter plates themselves. 

The hypotensive activity of A -tetrahydrocannabinol (xix) in animals suggests it as a new lead. Development of tolerance to this effect may involve an immunogenic reaction. ... 

The structural change that can occur in a protein molecule on interfadal adsorption is a concern for the biopharmaceuticals. Structurally altered molecules can result in bulk protein aggregation over time, enhancing the risk of immunogenic reactions if injected into the body [89]. Different studies have shown that protein can undergo denaturation at the interface [37,62,90-94[. 

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