Human autoimmune disorders arise when the immune system fails to maintain self-tolerance, leading to attacks on the body’s own tissues. This multiple-choice question tests understanding of mechanisms that either promote or prevent autoimmunity. The correct answer is (c) P, Q, as these directly contribute to disease development.​

Option Analysis

• P. Inability to eliminate self-reactive lymphocytes: This promotes autoimmunity. Self-reactive lymphocytes, which recognize self-antigens, are normally deleted or inactivated during development in the thymus or bone marrow; failure allows their survival and activation, causing diseases like multiple sclerosis or type 1 diabetes.​

• Q. Generation of auto-antibodies: This promotes autoimmunity. Auto-antibodies target self-antigens, forming immune complexes that damage tissues, as seen in systemic lupus erythematosus (SLE) or rheumatoid arthritis.​

• R. Ability to eliminate self-reactive T-cells: This prevents autoimmunity. Effective deletion of self-reactive T-cells in the thymus via negative selection maintains central tolerance; its presence inhibits disease.​

• S. Induction of regulatory T-cells in the thymus: This prevents autoimmunity. Regulatory T-cells (Tregs) suppress self-reactive responses; their thymic induction enforces peripheral tolerance, and defects contribute to disorders only if impaired.​

Correct Answer Explanation

Options P and Q represent breakdowns in immune tolerance: P allows autoreactive cells to persist, while Q enables antibody-mediated damage. In contrast, R and S are protective mechanisms. Thus, (c) P, Q identifies the promoting conditions. This aligns with core immunology, where autoimmunity stems from defective lymphocyte control rather than effective regulation.​