ULTRASTRUCTURAL-STUDY ACROSS THE LEPROSY SPECTRUM

We have carried out a systematic ultrastructural study of the bacilli, the cell-mediated response in the host, and the dermal microvasculatu re in lepromatous (LL), borderline lepromatous (BL), and borderline tu berculoid (BT) types of active leprosy (eight cases). In the types of least resistance (LL and BL), macrophages with large cytoplasmic proce sses were observed; in addition, numerous peripheral vacuoles were fou nd in BL. Mast cells were abundant and vascular alterations constant. BT macrophages showed more regular outlines and multivacuolated cytopl asms with plentiful rough endoplasmic reticulum. Giant cells were scar ce. Bacilli, both isolated and in globi, were contained within the vac uoles and appeared constantly in macrophages and endothelial and Schwa nn cells in LL and BL. Conversely, in BT they were found singly, infre quently in the endothelial cells, and not at all in Schwann cells. For ms in the process of destruction or degradation were more common than intact forms, in which the symmetric outline of the membrane could be seen clearly.