Author(s): Osamu Yoshida, Teruki Miyake, Yoichi Hiasa, Masanori Abe, Tetsuji Niiya
We examined whether antigen-specific immune responses are lower in mice with protein energy malnutrition (PEM mice) compared with nourished (control) mice. The mechanisms underlying reduced antigen-specific immune responses of PEM mice were evaluated through analysis of the functional capacities of antigen-presenting dendritic cells (DC). PEM mice were produced by subjecting male C57BL/6 mice for 52 wk to a daily food intake equivalent to 70% of the mean amount consumed by the control mice that consumed food ad libitum. PEM mice and control mice were immunized with hepatitis B vaccine containing hepatitis B surface antigen (HBsAg) at 52 wk and humoral and cellular immune responses to HBsAg were evaluated at 58 wk. Lymphoproliferative assays were performed to assess the functional capacities of lymphocytes and DC. After 52 wk of food restriction, PEM mice had a 49% lower body weight than controls, almost no subcutaneous fat, severe muscle wasting, and atrophied spleen. All control mice developed antibodies to HBsAg (anti-HBs) in the sera and HBsAg-specific lymphocytes in the spleen as a result of immunization with the hepatitis B vaccine. PEM mice, however, were almost unresponsive to immunization with the hepatitis B vaccine. In PEM mice, the numbers of spleen DC, the T lymphocyte stimulatory capacities of DC, and their production of IL-12p70 and IFN-γ was less than those of control mice (P < 0.05). We suggest that chronic undernutrition disrupts antigen-specific immune responses and that this disruption can be attributed at least in part to reduced frequencies and impaired functions of DC.