Malnutrition-Induced Involution of Lymph Nodes in Mice

Abstract

Immune suppression is one of the major factors affecting the pandemic outbreak of infectious diseases in societies where malnutrition is common. The thymus and spleen are known to respond to starvation via reductions in their size and functions, which is called thymic or splenic involution. However, almost no reports have been published on the response of lymph nodes, other secondary immune organs, to starvation. Therefore, we here examined the histological characters of lymph nodes of a mouse dietary restriction model. Dietary restriction for 48 h reduced the size of inguinal lymph nodes by 48%. Immunoreactivity to anti-immunoglobulin G antibody was reduced by the dietary restriction, along with a normal level of immunoglobulin M-immunoreactivity, suggesting inhibited immune capacity. Because splenic involution involves macrophages, we immunostained the lymph node sections to detect macrophages. The immunoreactivity to anti-ionized calcium-binding adaptor molecule 1 (IBA1)/allograft inflammatory factor 1 (AIF1) antibody was not changed by the dietary restriction. In contrast, anti-F4/80 antibody reactivities in medullary cord macrophages, interfollicular macrophages, and the macrophages located along trabeculae in the subcapsular sinus were reduced by the dietary restriction. These results indicate that, in addition to thymus and spleen, lymph nodes are also susceptible to starvation. Specific subpopulations of macrophages are reduced in the lymph nodes of starved mice.