The mouse local lymph node assay (LLNA) measures lymphocyte proliferation in draining lymph nodes of mice after topical application of a test material to the intact, non-occluded skin of both ears. There is a need to develop methods to evaluate the sensitization potential of chemicals and/or materials that are implanted or injected into the body (e.g. drugs. implanted medical devices, biologics), for which topical application in not a relevant route. In addition, it is important to distinguish between IgE mediated and cell mediated sensitizers. To evaluate the sensitization potential of implanted/injected materials, the LLNA was conducted using the subcutaneous route rather than the topical route. Two irritants (sodium lauryl sulfate (SLS) nonanoic acid), a T-cell mediated sensitizer (oxazolone), and a protein that is foreign to the mouse (human albumin) were evaluated using the subcutaneous route of administration. An IgE-mediated sensitizer (toluene diisocyanate; TDI) and a T-cell mediated sensitizer (DNFB) were used as positive controls. The irritant nonanoic acid did not induce lymphocyte proliferation compared to the vehicle control group. However, as seen with topical administration. SLS induced low level, significant lymph node cell proliferation at the two highest concentrations. Oxazolone and human albumin caused a significant concentration-dependent increase in lymphocyte proliferation versus the vehicle control. Phenotypic analysis conducted for groups of mice treated subcutaneously with vehicle (polyvinyl pyrrolidone; PVP), nonanoic acid, oxazolone, DNFB and TDI revealed a significant increases in the percent B220+ lymphocytes for the oxazolone, DNFB and TDI groups, whereas the nonanoic acid group was similar to the control. The percent IgE+B220+ lymphocytes increased from least to greatest in the oxazolone, DNFB and TDI groups, respectively whereas the nonanoic acid group was similar to the vehicle control group. TDI was associated with a 2-8 fold increase in the percent IgE+B220+ lymphocytes as compared to oxazolone or DNFB.
The Toxicologist. Society of Toxicology 39th Annual Meeting, March 19-23, 2000, Philadelphia, Pennsylvania