Tuberculosis. Light micrograph of a section through a lymph node showing a Langhans' cell (centre) caused by tuberculosis (TB). A Langhans' cell is an agglomeration of macrophage white blood cells caused by the infection. The nuclei of the macrophages are seen around its periphery. TB is a disease caused by infection with Mycobacterium tuberculosis bacteria. It can cause coughing, chest pain and fever, and may be fatal.