Draining lymph node cell activation in guinea pigs: comparisons with the murine local lymph node assay

Area of Science:

• Toxicology
• Immunology
• Dermatology

Background:

• The mouse local lymph node assay is a validated method for identifying contact sensitizers.
• Guinea pigs are the current standard species for regulatory assessment of chemical sensitization potential.

Purpose of the Study:

• To evaluate the feasibility and efficacy of a local lymph node assay in guinea pigs.
• To determine if this assay can identify contact sensitizing chemicals for regulatory purposes.

Main Methods:

• Ten known sensitizing chemicals and sodium lauryl sulphate were applied to guinea pig ears daily for three days.
• Draining lymph node cells were cultured, and proliferation was measured via [3H]thymidine incorporation.
• Lymph node weight was also assessed as a correlate of immune activation.

Main Results:

• All tested sensitizing chemicals, except benzocaine, induced significant lymph node cell proliferation.
• Proliferation responses were more pronounced at 24 hours compared to 48 hours in culture.
• Increased lymph node weight was observed for some sensitizers but was less sensitive than cell proliferation.

Conclusions:

• A local lymph node assay is feasible and effective in guinea pigs for identifying contact sensitizing chemicals.
• This assay provides a valuable alternative or supplement to existing methods for chemical safety assessment.
• Further research may explore enhancing guinea pig lymph node cell proliferation with factors like interleukin-2.