NATURAL-KILLER-CELL ACTIVITY IS ASSOCIATED WITH BRAIN ASYMMETRY IN MALE-MICE

The brain is known to modulate the immune system in an asymmetrical way. In mice, there is an association between handedness and immune response and it has also been shown that hemicortical ablation has opposite effects on some immune parameters. An association between autoantibody production and paw preference was previously observed in female mice, but not in males, suggesting that the association between immune reactivity and functional brain asymmetry is a sex-dependent phenomenon. In three independent experiments, natural killer (NK) cell activity, lymphocyte subset distribution, and mitogen-induced lymphoproliferation were assessed in male C3H OuJIco mice selected for handedness and after unilateral cortical ablation. Handedness was shown to be associated with NK cell activity but not with lymphocyte subset distribution or lymphoproliferation. Left-handers exhibited lower NK cell activity compared to right-handed or ambidextrous animals. In contrast to previous results in female mice, mitogen-induced lymphoproliferation was not associated with handedness in males. Left cortical ablations depressed NK cell activity, while right lesions had no effect. Neither left or right lesions affected lymphocyte subsets. No interaction between paw preference and side of the lesion was found in the modulation of NK cell activity. These and previous data show that the association between paw preference and immune reactivity varies according to the sex of the animal and the immunological parameters studied. This indicates that the brain may modulate different components of the immune system in different ways, through mechanisms apparently involving sex hormones. © 1991.