CTSD and leprosy: In addition, skin biopsy specimens of 4 different lepromatous leprosy patients taken from the border of the infection as defined by the depigmentation line were analyzed using TEM and immunogold labeling for M. leprae-specific anti-cell wall protein and lysosomal markers such as cathepsin D (Fig. 4 and Fig. S3), LAMP1, and CD63.