What is the role of immunologic tests in the diagnosis of leprosy?

Updated: Jun 05, 2020
  • Author: Darvin Scott Smith, MD, MSc, DTM&H; Chief Editor: Michael Stuart Bronze, MD  more...
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Immunologic tests include the following:

  • Polymerase chain reaction (PCR): PCR and recombinant DNA technology have allowed for the development of gene probes with M leprae–specific sequences. This technology can be used to identify the mycobacterium in biopsy samples, skin and nasal smears, and blood and tissue sections. [16]
  • Phenolic glycolipid-1: This is a specific serologic test based on the detection of antibodies to phenolic glycolipid-1. This test yields a sensitivity of 95% for the detection of lepromatous leprosy but only 30% for tuberculoid leprosy.
  • Lymphocyte migration inhibition test (LMIT): As determined by a lymphocyte transformation and LMIT, cell-mediated immunity to M leprae is absent in patients with lepromatous leprosy but present in those with tuberculoid leprosy.
  • Lepromin skin test (not available in the United States): Although not diagnostic of exposure to or infection with M leprae, this test assesses a patient's ability to mount a granulomatous response against a skin injection of killed M leprae. Patients with tuberculoid leprosy or borderline lepromatous leprosy typically have a positive response (>5 mm). Patients with lepromatous leprosy typically have no response.
  • Contact or family screening for history of leprosy

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