Immunology of leprosy

Area of Science:

• Immunology
• Infectious Diseases
• Dermatology

Background:

• Host immune responses to Mycobacterium leprae are crucial for infection control.
• Immune responses also cause immunopathological damage to skin and nerves.
• The spectrum of leprosy, from tuberculoid to lepromatous, is based on varied immune responses.

Purpose of the Study:

• To discuss the cellular interactions underlying the leprosy spectrum.
• To review the antigenic components of Mycobacterium leprae.
• To explore mechanisms of M. leprae immune evasion and chronic inflammation.

Main Methods:

• Review of cellular interactions in leprosy.
• Brief review of Mycobacterium leprae antigenic components.
• Discussion of M. leprae immune evasion strategies.

Main Results:

• Mycobacterium leprae evades macrophage defenses, leading to bacillary persistence.
• Persistent bacilli and cytokine release cause chronic granulomatous inflammation.
• Immune responses are dynamic, with spontaneous variations causing leprosy reactions (Type I and II).

Conclusions:

• The factors determining tuberculoid vs. lepromatous leprosy patterns require elucidation.
• The triggers for leprosy reactional episodes remain to be identified.
• Further research is needed to understand the complex host-pathogen interactions in leprosy.