Lupus and leprosy: beyond the coincidence

Systemic lupus erythematous (SLE) is an autoimmune disease that presents an increased susceptibility to infections which may trigger reactivation. Disease flares have been mostly associated with parvovirus B19, cytomegalovirus, EBV and Mycobacterium tuberculosis infections, but it is probable that many other agents may also induce innate and adaptive immune system stimulation including the production of autoantibodies as ANA, anti nDNA and anti-ß2-GPI mainly in lepromatous leprosy. Mycobacterium leprae not only may determine symptoms that mimic lupus flares, including autoantibodies production, but could also act as a trigger for lupus reactivation; however, its association is still not fully explored. As demonstrated for tuberculosis, it is quite possible that molecular mimicry may also be involved in the interface of these two diseases. Some studies reported shared epitopes among idiotypes derived from 8E7 and TH9 lepromatous antibodies and those obtained from SLE patients, and it could partially explain the triggering phenomenon of SLE caused by M. leprae. We report and discuss three Brazilian patients whose disease was inactive and presented disease flares concurrently with the diagnosis of leprosy.