What Is a Reactive Lymph Node?

The lymph nodes are distributed throughout the body and form an integral part of the lymphatic system. Lymphocytes and macrophages, which combat disease-causing elements, are clustered around these nodes. During exposure to harmful substances, these nodes swell in response to elevated levels of inflammatory cells in the affected area. Typically, enlargement of the lymph nodes occurs in the neck, armpits, groin and under the chin.