Splenic natural killer cell activity in wasted, protein-energy malnourished weanling mice

Abstract

The objective of this investigation was to assess the influence, on splenic natural killer (NK) cell activity, of wasting malnutrition imposed according to a protocol known to depress a variety of acquired immune functions in weanling animals. The spleen was selected as a physiologically important site of NK cell action. The weanling stage of life was important to study because NK activity undergoes critical ontogenetic change during this period. Weanlings of two unrelated mouse strains, C57BL/6J and CBA/J, were allowed ad libitum access for 14d to a complete purified diet or to an isoenergetic low-protein (0.5%) formulation. The imbalanced diet produced wasting disease in both strains which was comparable to that shown previously to depress both humoral and acquired cell-mediated immunity. NK activity was assessed as innate lytic action against YAC-1 targets and, on a whole-spleen basis, was depressed in animals from both strains subjected to the low-protein protocol. Inclusion of a baseline control group to delineate the pre-experimental starting point permitted distinction between true depression in NK activity and inhibition of ontogeny. The results extend knowledge concerning immunodepression in wasting malnutrition, and provide an experimental foundation from which to develop an integrated understanding of NK cell biology within the systemic pathophysiology of wasting malnutrition.