Enhanced Local Lymph Node Assay (Flow Cytometry based)
The Mouse Local Lymph Node Assay is now accepted by the EPA, OECD, and FDA as the preferred “stand-alone alternative” to the Guinea Pig Sensitization Test. MB Research offers a “Standard LLNA” based upon OECD TG429 and EPA OPPTS 870.2600 guidelines. In addition, for problem test substances and irritants, MB Research also offers an “Enhanced LLNA” using Flow Cytometry to allow the evaluation of optional immunophenotypic markers which discriminate “true sensitizers” from “false-positive irritants”.
During the “induction phase” of sensitization, following exposure to a sensitizing test substance, lymphocyte proliferation occurs in the local lymph node. The LLNA measures increased proliferation of lymphocytes in the auricular lymph nodes (which drain the site of exposure; ears). Proliferation is assessed by determining the incorporation of the thymidine analog, bromodeoxyuridine (BrdU), into the DNA of lymph node cells using flow cytometric method.
This “Enhanced LLNA” reduces background noise and false positives, by quantitatively assessing irritation, (via ear swelling) and by incorporating optional immunophenotype analysis to resolve and discriminate false-positive irritants (%B220+, CD3+, CD69+, I-Ak+ cells).
Enhanced Local Lymph Node Assay