An electron microscopic study on macrophages and lymphocytes in lepromatous and borderline leprosy.

We describe how macrophages are activated and phagocytose mycobacteria in lepromatous leprosy. The differentiation of macrophages into epithelioid cells and into giant cells in borderline leprosy is shown. Close apposition between macrophages and lymphocytes is seen in those areas where mycobacteria disintegrate inside macrophages.