Question 1

Antibodies to cyclic citrullinated proteins (anti-CCP)are specific diagnostic indicators for:

Accepted Answer

Antibodies to cyclic citrullinated proteins are highly specific for rheumatoid arthritis and are not typically seen in other autoimmune or inflammatory conditions such as type 1 diabetes mellitus, celiac disease or biliary cirrhosis.

Question 2

Citrullinated proteins:

Accepted Answer

Citrullination is a post-translational modification of arginine residues which generates citrulline residues in proteins. This modification changes the charge and structure of the protein, and citrullinated proteins have been implicated in various diseases, particularly autoimmune disorders such as rheumatoid arthritis. Citrulline is not an atypical type of amino acid but rather a modified form of arginine. Therefore, choice B is the best answer.

Question 3

Systemic lupus erythematosus can be distinguished from rheumatoid arthritis on the basis of which of the following?

Accepted Answer

Deposition of immune complexes in the kidneys is a characteristic feature of systemic lupus erythematosus, whereas it is not typical of rheumatoid arthritis. Joint pain and inflammation are common symptoms in both conditions and are therefore not sufficient to distinguish between them. Antibody to acetylcholine receptors is associated with myasthenia gravis, which is a different autoimmune disorder.

Question 4

Screening and confirmation tests for antinuclear antibodies are typically performed by:

Accepted Answer

The most common screening test for antinuclear antibodies is indirect immunofluorescence (IIF). Confirmation tests can include enzyme immunoassay (EIA) or other methods. Therefore, choice B is the best answer as it suggests performing IIF followed by EIA.

Question 5

A 25-year-old female sees her physician because of swelling in the joints of her hands and generally feeling tired and rundown.A slide agglutination test for antibody directed against IgG is positive.What is the most likely cause of her symptoms?

Accepted Answer

The positive slide agglutination test for antibody directed against IgG is a common laboratory test for rheumatoid arthritis. The swelling in the joints of the hands and fatigue are also typical symptoms of this autoimmune disorder. Autoimmune hemolytic anemia, mononucleosis, and syphilis do not typically present with these symptoms or a positive slide agglutination test for IgG.

Question 6

Antibodies directed against thyroglobulin represent a significant finding in which of the following autoimmune diseases?

Accepted Answer

Antibodies directed against thyroglobulin are specific to Hashimoto's thyroiditis, an autoimmune disease that targets the thyroid gland. Myasthenia gravis is associated with antibodies against acetylcholine receptors, multiple sclerosis is associated with antibodies against myelin, and contact dermatitis is not typically associated with autoimmune antibodies.

Question 7

Central tolerance,in which lymphocytes learn to distinguish between self-antigens and foreign antigens,takes place in the thymus and:

Accepted Answer

Central tolerance takes place in the thymus and bone marrow. The spleen and lymph nodes are peripheral lymphoid organs where mature lymphocytes encounter foreign antigens. The liver is not directly involved in lymphocyte development or central tolerance.

Question 8

Which of the following is considered a systemic autoimmune disease?

Accepted Answer

Systemic lupus erythematosus (SLE) is considered a systemic autoimmune disease, as it can affect multiple organs and tissues in the body. Multiple sclerosis, Graves disease, and myasthenia gravis are all autoimmune diseases, but they are not considered systemic as they primarily affect specific organs or tissues.

Question 9

A perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA)staining pattern consists of:

Accepted Answer

A perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA) staining pattern consists of fluorescence surrounding the lobes of the nuclei.

Question 10

In antinuclear antibody testing,HEp-2 cells:

Accepted Answer

HEp-2 cells are used as the source of the antigen in antinuclear antibody testing, where they provide a substrate for detecting autoantibodies present in the patient's serum.

Question 11

A 35-year-old female experiences difficulty in walking,and her hands and feet are numb from time to time.Suspecting a disease involving the central nervous system,her physician orders magnetic resonance imaging (MRI).The MRI reveals lesions on the myelin sheath.What is the most likely disease?

Accepted Answer

Multiple sclerosis is a disease involving the central nervous system where the myelin sheath is damaged, leading to symptoms such as difficulty in walking and numbness of the hands and feet. Goodpasture's syndrome is a rare autoimmune disease affecting the lungs and kidneys, whereas multiple myeloma is a cancer of plasma cells. Graves disease is a thyroid disorder, and it does not involve damage to the myelin sheath.

Question 12

A 16-year-old male goes to his physician for an annual checkup.A routine urinalysis indicates the presence of blood,an increase in protein,and an increase in urea.The young man reports that he has been feeling tired and has a persistent cough.The doctor orders additional laboratory testing,including a serum test for rheumatoid factor,antinuclear antibody testing,anti-streptolysin O testing,and testing for the presence of anti-basement membrane antibodies.Only the latter test was positive.What disease is the most likely cause of the symptoms?

Accepted Answer

The presence of blood and protein in the urine, along with an increase in urea, suggest renal involvement. The positive test for anti-basement membrane antibodies indicates Goodpasture's syndrome, an autoimmune disorder that can cause lung and kidney damage. The patient's tiredness and persistent cough also fit with the diagnosis. Systemic lupus erythematosus can cause similar symptoms, but the additional laboratory tests were negative for markers of that disease. Multiple sclerosis and rheumatoid arthritis would not be expected to cause the urinary and respiratory symptoms seen in this case.

Question 13

Which mechanism is involved in peripheral tolerance to self-antigens?

Accepted Answer

Peripheral tolerance involves mechanisms that occur after T cells have matured and left the thymus, including the inhibition of co-stimulatory signals from antigen-presenting cells, which helps prevent the activation of self-reactive T cells.

Question 14

Homogeneous staining of the nucleus in an antinuclear antibody test indicates:

Accepted Answer

Homogeneous staining of the nucleus in an antinuclear antibody test typically indicates the presence of antibodies to DNA-histone complexes, also known as anti-dsDNA antibodies. This pattern is commonly seen in patients with systemic lupus erythematosus (SLE).

Question 15

A speckled nuclear pattern in an antinuclear antibody test indicates:

Accepted Answer

A speckled nuclear pattern on an antinuclear antibody test indicates the presence of antibodies to extractable nuclear antigens (ENAs). These are typically antibodies to proteins found in the nucleus, such as SSA, SSB, RNP, and Sm, and are associated with a variety of autoimmune diseases, including systemic lupus erythematosus (SLE) and Sjogren's syndrome.

Quiz 15: Autoimmunity

Antibodies to cyclic citrullinated proteins (anti-CCP) are specific diagnostic indicators for: