In the course of sensitization and airway challenge with allergen, immunological and histological changes occur that can be measured to assess the sensitization efficacy. In particular, a shift in the responsiveness of allergen-specific T cells with preferential production of TH2-type cytokines (e.g., IL-4 and IL-5) and a marked eosinophilic inflammation of the airways are hallmarks of allergen sensitization.
Table 15.18.2 indicates some of the assays that provide useful information about the immune status of animals with airway inflammation, although it is not a complete list. Experimental objectives will dictate the choice of assay(s) to be used. Assays are typically performed either on the same day as the measurement of lung function (day 12, for the Alternate Protocol) or the next day (day 33, for the Basic Protocol).
Animal Models of Airway Sensitization
Table 15.18.2 Relevant Assays of Immune Status Described Elsewhere in This Manual
Allergen-specific T cell proliferation unit 3.12
Measurement of cytokine production (e.g., IL-4, IL-5, IFN-y) following stimulation with allergen or T cell activators (see Table 3.12.1)
Enumeration of eosinophils harvested from bronchioalveolar lavages
Enumeration of eosinophils in sections of lung tissue units 6.3, 6.5 & 6.8
Measurement of allergen-specific Ig unit 2.2 levels
The allergen used to stimulate cells should be tested at several doses to optimize conditions for T cell proliferation.
Other units in Chapter 6 for measuring TH2-type cytokines can also be used.
The Support Protocol in this unit describes the use of human eosinophils, but the procedure can also be used to stain mouse cells. This unit describes several immunohistochemistry protocols. Modifications of the Basic Protocol and Alternate Protocol 2 (i.e., using none of the immunologic reagents) can be used to stain cells with hematoxylin/eosin. This unit includes a protocol in which a sandwich ELISA is used for isotype detection. It can easily be adapted to measure allergen-specific (and isotype-specific) Ig levels by coating wells with the allergen in lieu of anti-isotype antibodies and then detecting the bound Ig using anti-isotype antibodies.
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