Membrane attack complex in thickened cutaneous sensory nerves of leprosy patients.

Membrane attack complex (MAC) is a terminal end product produced as a result of complement activation. The deposition of MAC, in tissues, is known to have a local tissue damaging effect in several clinical conditions. Therefore, an attempt was made to demonstrate MAC in peripheral nerve biopsies, collected from leprosy patients. Interestingly, we could demonstrate deposition of MAC in involved cutaneous sensory nerves from most of the lepromatous leprosy patients. Contrary to this, majority of nerve biopsies from tuberculoid leprosy patients did not stain for MAC. Though MAC positive sections showed reactivity for S-protein, our observations support the possibility that MAC, either acting directly or indirectly, may be implicated in nerve damage, at least, in lepromatous leprosy patients.