NK-cell activity in immunotoxicity drug evaluation.

Area of Science:

• Immunotoxicology
• Drug Safety Assessment
• Flow Cytometry

Background:

• European guidance (CPMP/SWP/1042/99) highlights NK-cell activity and lymphocyte subsets as alternatives to antibody response testing for drug immunotoxicity.
• These assays are recommended for routine inclusion in repeated dose-toxicity studies in rodents.
• The conventional method for assessing NK-cell activity is the 51Cr-release assay.

Purpose of the Study:

• To introduce and evaluate a novel flow-cytometric assay for measuring NK-cell activity in rat peripheral blood.
• To compare the sensitivity and practicality of the new assay against the standard 51Cr-release assay.
• To assess the utility of the flow-cytometric method for detecting drug-induced immunotoxicity.

Main Methods:

• Adaptation of a flow-cytometric assay for peripheral blood samples from rats.
• Measurement of NK-cell activity using the new flow-cytometric method.
• Comparison of results with the conventional 51Cr-release assay.

Main Results:

• The flow-cytometric assay does not necessitate separate animal groups, allowing for repeated testing on the same animals.
• The assay is demonstrated to be at least as sensitive as the traditional 51Cr-release assay.
• The method is suitable for routine use in toxicity studies.

Conclusions:

• A new flow-cytometric assay provides a sensitive and efficient alternative for assessing NK-cell activity in drug safety studies.
• This method facilitates repeated measurements and reduces animal usage compared to conventional assays.
• The assay is a valuable tool for detecting potential immunotoxic effects of new human drugs.