Differences in NK cell function in mice bred for high and low aggression: genetic linkage between complex behavioral...

Area of Science:

• Immunology
• Behavioral Genetics
• Animal Behavior

Background:

• Previous studies identified differences in cellular immune responsiveness between high and low aggressive mouse lines (Institute for Cancer Research - ICR).
• Low aggressive mice exhibit lower natural killer (NK) and T cell activity, correlating with increased tumor susceptibility.

Purpose of the Study:

• To investigate the relationship between aggression levels and NK cell activity in selectively bred mice.
• To test whether NK cell activity differences are dependent on aggression expression or independently linked genetically.

Main Methods:

• Experiment 1: Manipulated postweaning social experiences (single, group-housed within/between lines) in male mice to assess effects on aggression and NK cell activity.
• Experiment 2: Compared NK cell activity in nulliparous females of high and low aggressive lines, focusing on a context where females display aggression (postpartum intruder response).

Main Results:

• Social housing conditions did not alter the line-specific differences in NK cell activity in males.
• NK cell activity differences between high and low aggressive lines were solely attributable to genetic line, not social experience.
• Females of the low aggressive line showed reduced NK cell activity compared to high aggressive females, mirroring male patterns.

Conclusions:

• Findings support the hypothesis of genetic linkage between genes influencing aggression and immune traits.
• The observed association could stem from pleiotropic gene effects or a fortuitous genetic association during selective breeding.