Antigen challenge assay

When lodoxamide tromethamine was administered orally to reactor Ascaris monkeys, excellent inhibition of both lung function parameters was seen Indicating a reversal of antigen challenge induced changes. Table 11 summarizes the activity of lodoxamide tromethamine and its duration of effect vAien dosed orally. This table also shows that when the optimal time (30 min.) is used to assay a dose response, inhibition can be seen as low as 5.0 mg/kg. Table 12 shows that when lodoxamide tromethamine was administered i.v. 5 min. before ascaris aerosolization (0.16 ml aerosolized in 50 respirations), protection was seen even at 0.001 mg total dose per animal (Table 13). 

We have seen that IgM is the first isotype of humoral antibody produced in response to antigenic challenge and that if the challenge persists it is replaced by IgG isotype. If the infection is chronic and the antigen persists, or reexposure occurs, higher levels of IgG will be produced. This information is valuable to the immunoassayist because when total antibody (all isotypes) is assayed, an increase in antibody titer over time is indicative of a current infection. This is also true when isotype-specific second antisera are used. The comparison of IgM and IgG levels is also a useful indicator. 

Anthrax Medium from cuitures of B. anthracis 1 Separation of protective antigen from medium 2 Adsorption 3 + 3 quantal assay in guinea-pigs using challenge with B. anthracis Exclusion of live 6. anthracis and of anthrax toxin... 

The suppression of DTH (in vivo) by CD8-I-Tregs affords a direct demonstration of the suppressive effects of these cells on effector T cells because adoptive transfer assays demonstrate a suppressive effect on the DTH response within 24 h of the introduction of CD8-I- Tregs into the challenge site for DTH at the time of challenge with the antigen. The ability of CD8-I- suppressor T cells to suppress directly DTH in vivo has been measured by the local adoptive transfer assay (LAT) that transfers DTH to naive recipients by... 

As discussed above, the LTS facilitates investigations of the mechanisms that enable the suppression of DTH by CD8-f Tregs because the assay is complete within 24 h. In other words, to probe the mechanisms and antigen specificity of suppression, manipulations can be made that only influence the suppression of the DTH response after the immunized mice are challenged. 

The issue of which antibody to select for an assay is not a new problem. Certainly anyone involved in the development of an immunoassay has been faced with this choice. Consider attempting to create a multianalyte, microarray-based micro-ELISA of modest density (10 to 100 analytes) and determining which capture antibodies to use based upon their affinities, stabilities, and cross-reactivities. For a sandwich assay, add in the 10 to 100 analyte-specific secondary (reporter) antibodies and determine their levels of cross-reactivity with each other and with the specified antigens and capture antibodies. In other words, achieving high performance for all analytes with a microarray immunoassay is indeed a formidable challenge. 

Assays to measure cell-mediated immunity, with either in vivo sensitization and intradermal challenge (delayed-type hypersensitivity) or in vitro measurements of T cell responses to antigens or mitogens. 

Most of the initial studies used in vitro proliferation or IL-2 production assays to demonstrate induction of T cell anergy. In some cases, T cell anergy was also shown to operate in vivo [30, 38], but not in others. Thus, in vivo SAg challenge of anergic mice induced secretion of IL-2 and other cytokines in vivo [39, 40], Further, CD4+ T cells that were anergic when exposed to the antigen in vitro were able to induce efficient B cell responses in vivo [13, 41, 42],... 

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