A draining lymph node assay (DLNA) for assessing the sensitizing potential of proteins

Area of Science:

• Immunotoxicology
• Allergenicity Assessment
• Respiratory Sensitization

Background:

• Identifying respiratory sensitization potential of novel proteins is crucial.
• Existing models for assessing protein sensitization can be complex.
• A simple, predictive model is needed for early-stage assessment.

Purpose of the Study:

• To evaluate the mouse draining lymph node assay (DLNA) as a predictive model for respiratory protein sensitization.
• To compare different routes of exposure (dermal, intranasal, oropharyngeal aspiration) for their efficacy in the DLNA.
• To establish a rank order of protein sensitization potency using the DLNA.

Main Methods:

• Female BALB/c mice were dosed with proteins (Subtilisin Carlsberg, ovalbumin, beta-lactoglobulin, keyhole limpet hemocyanin) via dermal, intranasal (IN), or oropharyngeal aspiration (OP) routes.
• Lymph node proliferation was measured in draining lymph nodes (auricular, superficial cervical, tracheobronchial) on day 6.
• Molecular characterization of tracheobronchial lymph nodes (TBLN) was performed.

Main Results:

• Intranasal and oropharyngeal aspiration routes showed dramatic and reproducible responses in the tracheobronchial lymph nodes (TBLN).
• Dermal administration did not stimulate lymph node proliferation.
• A rank order of protein potency was established: Subtilisin Carlsberg > keyhole limpet hemocyanin > ovalbumin > beta-lactoglobulin.
• Endotoxin levels had minimal impact on the observed rank order.

Conclusions:

• The mouse DLNA, particularly with intranasal or oropharyngeal aspiration, is a viable starting point for assessing protein respiratory sensitization potential.
• The assay effectively differentiates between proteins with varying allergenic potencies.
• Further research is needed to clarify the relevance of molecular profiles in TBLN for predicting allergic potential.