Paper I — 2024 March (Supplementary) (2010 Scheme) — Q12

Paper I

2024 March (Supplementary) (2010 Scheme) · 40 marks · 120 min

Question

Write TWO mechanisms of autoimmunity

Q122 marksShort Notes★✓

Answer

Two mechanisms of autoimmunity:

1. Molecular mimicry — structural similarity between a microbial antigen and a self-antigen leads to a cross-reactive immune response against self-tissue following infection (e.g., rheumatic fever, where antibodies against streptococcal M protein cross-react with cardiac tissue).
2. Failure of self-tolerance — defective central (thymic/bone marrow) clonal deletion of self-reactive lymphocytes, or failure of peripheral control mechanisms (anergy, regulatory T-cell suppression), allowing autoreactive lymphocyte clones to persist and become activated against self-antigens.

(Other valid examples: release of sequestered self-antigens; polyclonal B-cell activation; genetic susceptibility via HLA associations; epitope spreading.)

Related Concepts

1. 1Autoimmunity

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