Vitamin A Deficiency in Rats Induces Langerhans Cells in the Iliac Lymph Nodes Draining to the Squamous Metaplastic Urinary Bladder

We previously observed Langerhans cells (LC) in the squamous metaplastic urinary bladder in rats fed a vitamin A-deficient diet. Here we report the finding of LC in the iliac lymph nodes, one of the abdominal lymph nodes draining to the urinary bladder. LC had previously only been observed in the superficial and hilar lymph nodes, but never in the abdominal lymph nodes. This is also the first observation of Birbeck granule (BG)-positive LC in the iliac lymph nodes. LC were not found in the transitional mucosa of the urinary bladder. In the present experiments, the LC were observed in both the squamous metaplastic mucosa and lamina propria of the urinary bladder, and also in the iliac lymph nodes, which drain into the urinary bladder. BG-positive LC may mature not only in the squamous epithelia, but also in squamous metaplastic mucosa. LC in the lamina propria of the urinary bladder might migrate to the iliac lymph nodes, which are regional lymph nodes, where they could function in antigen presentation. LC in the skin play a role in antigen-antibody interactions, and the squamous metaplastic mucosa of the urinary bladder may be a similar environment, in which LC in the mucosa can migrate to the regional lymph nodes.