Autoimmunity and Autoimmune Diseases — MCQs
Which of the following auto antibodies is most likely to be present in a patient with systemic lupus erythematosus?
A 45-year-old female presents with dry eyes, dry mouth, and joint pain. Which of the following antibodies is most indicative of the suspected condition?
Which of the following is NOT a feature of Autoimmune Polyglandular Syndrome type 1 (APS-1)?
Most strongly associated with rheumatoid arthritis among the following is?
Which is the rheumatoid arthritis autoantibody?
HLA associated with Rheumatoid arthritis is?
Anti ds DNA is most specific for:
Increased susceptibility to N. meningitidis infections is associated with deficiency of which complement component:
Which of the following statements about Grave's disease is false?
Which one of the following statements about Graves' disease is FALSE?
Autoimmunity and Autoimmune Diseases Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following auto antibodies is most likely to be present in a patient with systemic lupus erythematosus?
- A. Antiphospholipid
- B. Anti-Ro
- C. Anti- ds DNA (Correct Answer)
- D. Anti-RNP
Explanation: ***Anti-ds DNA*** - **Anti-double-stranded DNA (anti-dsDNA)** antibodies are highly specific for **Systemic Lupus Erythematosus (SLE)** and are included in the classification criteria [1]. - Their levels often correlate with disease activity, especially in cases with **lupus nephritis** [1]. *Antiphospholipid* - While **antiphospholipid antibodies** can be present in SLE patients (leading to **secondary antiphospholipid syndrome**), they are not the most characteristic or diagnostic autoantibody for SLE itself. - These antibodies are primarily associated with a **prothrombotic state** and recurrent miscarriages. *Anti-Ro* - **Anti-Ro (SSA) antibodies** are associated with SLE, particularly with **cutaneous lupus**, **neonatal lupus**, and **Sjögren's syndrome**, but they are not as specific as anti-dsDNA for the general diagnosis of SLE [1]. - Patients with anti-Ro antibodies may have a higher risk of **photosensitivity** [1]. *Anti-RNP* - **Anti-RNP antibodies** are found in patients with SLE, but they are most characteristically associated with **Mixed Connective Tissue Disease (MCTD)**. - Their presence in SLE often correlates with less severe renal involvement but may indicate **myositis** or **Raynaud's phenomenon**.
Question 2: A 45-year-old female presents with dry eyes, dry mouth, and joint pain. Which of the following antibodies is most indicative of the suspected condition?
- A. Anti-Ro/SSA antibodies (Correct Answer)
- B. Anti-histone antibodies
- C. Anti-thyroid peroxidase antibodies
- D. Anti-phospholipid antibodies
Explanation: ***Anti-Ro/SSA antibodies*** - The patient's symptoms of **dry eyes (xerophthalmia)**, **dry mouth (xerostomia)**, and **joint pain** are classic manifestations of **Sjögren's syndrome**, a chronic autoimmune disease. [1] - **Anti-Ro/SSA antibodies** are highly specific for Sjögren's syndrome, particularly in patients with primary Sjögren's. [1] *Anti-histone antibodies* - These antibodies are most commonly associated with **drug-induced lupus erythematosus**, a condition characterized by lupus-like symptoms that develop after exposure to certain medications. - The clinical presentation of dry eyes and dry mouth is not the primary distinguishing feature of drug-induced lupus. *Anti-thyroid peroxidase antibodies* - These antibodies are a hallmark of **Hashimoto's thyroiditis**, an autoimmune disease affecting the thyroid gland and leading to hypothyroidism. [2] - While Sjögren's syndrome can coexist with other autoimmune conditions, anti-thyroid peroxidase antibodies do not directly indicate Sjögren's. *Anti-phospholipid antibodies* - These antibodies are primarily associated with **antiphospholipid syndrome**, a thrombophilic disorder characterized by arterial or venous thrombosis and/or adverse pregnancy outcomes. - They are not directly indicative of the sicca symptoms seen in Sjögren's syndrome.
Question 3: Which of the following is NOT a feature of Autoimmune Polyglandular Syndrome type 1 (APS-1)?
- A. Mucocutaneous candidiasis
- B. Addison's disease
- C. Hypoparathyroidism
- D. Autoimmune thyroiditis (Correct Answer)
Explanation: ### Autoimmune thyroiditis - **Autoimmune thyroiditis** is a key component of **Autoimmune Polyglandular Syndrome type 2 (APS-2)**, not APS-1 [1]. - APS-1 is distinguished by its classic triad, which does not include autoimmune thyroiditis as a primary feature [1]. ### Mucocutaneous candidiasis - **Chronic mucocutaneous candidiasis** is a defining feature of APS-1, affecting nearly all patients [1]. - This fungal infection is often the **first symptom** to appear in patients with APS-1. ### Addison's disease - **Addison's disease (primary adrenal insufficiency)** is a highly prevalent component of APS-1, occurring in over 80% of patients [1]. - It results from the autoimmune destruction of the adrenal cortex. ### Hypoparathyroidism - **Hypoparathyroidism** is a crucial diagnostic criterion for APS-1, occurring in over 70% of affected individuals [1]. - It leads to **hypocalcemia** due to inadequate parathyroid hormone production.
Question 4: Most strongly associated with rheumatoid arthritis among the following is?
- A. HLA B27
- B. HLA DR4 (Correct Answer)
- C. HLA DQ1
- D. HLA DR8
Explanation: ***HLA DR4*** - **HLA-DR4** is the **MHC Class II allele** most strongly associated with an increased risk and severity of **rheumatoid arthritis (RA)**. - It is thought to contribute to RA pathogenesis by presenting specific peptides that activate **auto-reactive T cells**, initiating the autoimmune response. *HLA B27* - **HLA-B27** is primarily associated with **seronegative spondyloarthropathies**, such as **ankylosing spondylitis** and **reactive arthritis**. - It has no significant association with **rheumatoid arthritis**. *HLA DQ1* - While a variety of **HLA-DQ alleles** are involved in autoimmune diseases, **HLA-DQ1** is not among the primary genetic associations for **rheumatoid arthritis**. - Its pathogenic role is more commonly studied in other conditions, such as **coeliac disease**, though various subtypes exist. *HLA DR8* - **HLA-DR8** has some associations with certain autoimmune conditions, such as **primary biliary cholangitis** and **Crohn's disease**. - It is not considered a primary or strong genetic risk factor for **rheumatoid arthritis**.
Question 5: Which is the rheumatoid arthritis autoantibody?
- A. Anti DLE
- B. Anti CCP (Correct Answer)
- C. Anti ds DNA
- D. Anti histone
Explanation: ***Anti CCP*** - **Anti-Citrullinated Protein Antibodies (CCP)** are highly specific for **rheumatoid arthritis** and are used for diagnosing this condition. - A positive **Anti-CCP** test can indicate the presence of **rheumatoid arthritis** even before clinical symptoms appear. *Anti histone* - This antibody is primarily associated with **drug-induced lupus erythematosus**, not rheumatoid arthritis. - It identifies a **response** to medications, rather than being a specific marker for a rheumatic condition like RA. *Anti DLE* - Suggests antibodies related to **discoid lupus erythematosus**, not rheumatoid arthritis. - These antibodies do not correlate with inflammatory joint disease or diagnosis of RA. *Anti ds DNA* - Commonly associated with **systemic lupus erythematosus** (SLE) rather than rheumatoid arthritis [1]. - While relevant for lupus, it lacks specificity for diagnosing rheumatic arthritis; ANA testing is noted as not useful in diagnosing RA specifically [1].
Question 6: HLA associated with Rheumatoid arthritis is?
- A. HLA-Cw6
- B. HLA-DR4 (Correct Answer)
- C. HLA-B8
- D. HLA-B27
Explanation: ***HLA-DR4*** - **HLA-DR4** is the **MHC Class II allele** most strongly associated with an increased risk and severity of **rheumatoid arthritis**, particularly in populations of European descent [2]. - This association is particularly relevant for the development of antibodies against **citrullinated proteins (ACPAs)**, a hallmark of more aggressive disease [1]. *HLA CW6* - **HLA CW6** is strongly associated with **psoriasis** and **psoriatic arthritis**, not rheumatoid arthritis. - It plays a role in the immune system's response in these conditions, distinct from the autoimmune mechanisms of rheumatoid arthritis. *HLAB8* - **HLA-B8** is associated with several autoimmune diseases, including **celiac disease**, **myasthenia gravis**, and Sjögren's syndrome, but not primarily with rheumatoid arthritis. - It reflects a broader predisposition to autoimmunity rather than a specific link to RA. *HLAB27* - **HLA-B27** is highly associated with **seronegative spondyloarthropathies**, such as **ankylosing spondylitis** and **reactive arthritis** [3]. - Its presence indicates a strong genetic predisposition for these conditions, which differ clinically and immunologically from rheumatoid arthritis [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1212. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1212-1214. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1214-1215.
Question 7: Anti ds DNA is most specific for:
- A. SLE (Correct Answer)
- B. Polymyositis
- C. Scleroderma
- D. Rheumatoid arthritis
Explanation: ***SLE*** - **Anti-dsDNA antibodies** are highly specific for **Systemic Lupus Erythematosus (SLE)** and are often associated with **lupus nephritis** and disease activity [1]. - Their presence, along with clinical criteria, helps in confirming the diagnosis of SLE. *Polymyositis* - Polymyositis is characterized by **proximal muscle weakness** and elevated muscle enzymes, but not primarily by anti-dsDNA antibodies [1]. - Key autoantibodies in polymyositis include **anti-Jo-1** and other myositis-specific antibodies. *Scleroderma* - **Scleroderma (Systemic Sclerosis)** is characterized by skin thickening and internal organ fibrosis, with autoantibodies like **anti-Scl-70** and **anti-centromere antibodies** [1]. - **Anti-dsDNA antibodies** are not typically found in scleroderma. *Rheumatoid arthritis* - **Rheumatoid arthritis (RA)** is a chronic inflammatory disorder primarily affecting the joints, and its characteristic autoantibodies are **rheumatoid factor (RF)** and **anti-citrullinated peptide antibodies (ACPA)**. - **Anti-dsDNA antibodies** are not relevant to the diagnosis of rheumatoid arthritis [1].
Question 8: Increased susceptibility to N. meningitidis infections is associated with deficiency of which complement component:
- A. C1-C4 deficiency
- B. C3 deficiency
- C. C5-C9 deficiency (Correct Answer)
- D. C2 deficiency
Explanation: ***C5-C9 deficiency*** - Deficiencies in **C5-C9 components** impair the formation of the **Membrane Attack Complex (MAC)**, which is crucial for lysing Gram-negative bacteria like **N. meningitidis**. - Patients with MAC deficiencies are at significantly higher risk for recurrent invasive **N. meningitidis** infections. *C1-C4 deficiency* - Deficiencies in **C1-C4 components** primarily affect the **classical complement pathway** and are associated with increased susceptibility to **bacterial infections** and **immune complex diseases** (e.g., SLE). - While these deficiencies compromise opsonization and inflammation, they are not specifically linked to recurrent **N. meningitidis** infections. *C3 deficiency* - **C3 deficiency** is a severe primary immunodeficiency leading to profound defects in complement activation via all pathways, affecting **opsonization** and the formation of the MAC. - This deficiency causes severe recurrent **pyogenic infections** due to encapsulated bacteria but is not as specifically or commonly linked to **N. meningitidis** as deficiencies in the terminal pathway. *C2 deficiency* - **C2 deficiency** is the most common complement deficiency and primarily impacts the **classical pathway**, leading to impaired opsonization and immune complex clearance. - It is often associated with recurrent infections (especially with encapsulated bacteria) and **lupus-like syndromes**, but not specifically increased susceptibility to **N. meningitidis** infections.
Question 9: Which of the following statements about Grave's disease is false?
- A. Autoimmune disorder
- B. Common in male (Correct Answer)
- C. Referred as toxic diffuse goiter
- D. Results in hyperthyroidism
Explanation: ***Common in male*** - Grave's disease has a **strong female preponderance**, with women being 5 to 10 times more likely to be affected than men [1]. - While it can occur in males, it is **not commonly seen** in this demographic compared to females [2]. *Autoimmune disorder* - Grave's disease is an **autoimmune disorder** where the body produces antibodies (primarily **TSH receptor antibodies**) that stimulate the thyroid gland [1], [2]. - These antibodies mimic the action of TSH, leading to **overproduction of thyroid hormones** [1]. *Results in hyperthyroidism* - The constant stimulation of the thyroid gland by **TSH receptor antibodies** leads to excessive synthesis and release of thyroid hormones [2]. - This overactivity of the thyroid gland is the primary cause of the **hyperthyroid state** characteristic of Grave's disease [2]. *Referred as toxic diffuse goiter* - The term **"toxic diffuse goiter"** accurately describes Grave's disease, as the entire thyroid gland is typically enlarged (**goiter**) and overactive (**toxic**) [1]. - The enlargement is usually **diffuse** rather than nodular, differentiating it from other causes of hyperthyroidism like toxic multinodular goiter.
Question 10: Which one of the following statements about Graves' disease is FALSE?
- A. Common in male (Correct Answer)
- B. Referred to as toxic diffuse goiter
- C. Results in hyperthyroidism
- D. Autoimmune disorder
Explanation: ***Common in male*** - Graves' disease is significantly **more common in females** than males, with a female-to-male ratio of approximately 7:1 [1]. It is a female predominant disease [2]. - The peak incidence is between the ages of 20 and 50 years, and it is the most common cause of **hyperthyroidism** in women [1], [2]. *Results in hyperthyroidism* - Graves' disease is characterized by the production of **autoantibodies** against the TSH receptor, leading to excessive stimulation of the thyroid gland [1]. - This overstimulation results in **increased synthesis and release of thyroid hormones**, causing a state of hyperthyroidism [2]. *Autoimmune disorder* - Graves' disease is a classic example of an **organ-specific autoimmune disease** [2]. - The immune system mistakenly produces antibodies that mimic the action of TSH, leading to thyroid overactivity [1]. *Referred to as toxic diffuse goiter* - The term "toxic" refers to the **hyperthyroid state** (thyrotoxicosis), and "diffuse goiter" describes the generally uniform enlargement of the entire thyroid gland [1]. - This terminology accurately reflects the typical presentation of Graves' disease, which involves an overactive, diffusely enlarged thyroid gland [2].
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