Autoimmunity and Immunodeficiency Practice Flashcards

Comprehensive practice questions covering autoimmune disorders, systemic and organ-specific diseases, testing methodologies, and primary immunodeficiencies based on the Clinical Serology lecture.

How are autoimmune diseases defined?

Disorders in which immune responses target self-antigens, resulting in damage to organs and tissues via a loss of self-tolerance.

What are autoantibodies?

$T$-cell-mediated immune responses directed against host antigen.

What is the definition of immunologic tolerance?

A state of immune unresponsiveness, particularly towards self-antigen.

Where does central tolerance occur?

In the primary lymphoid organs.

What is the process of central tolerance for $T$ cells?

As $T$ cells mature and encounter self-antigens, any cells that show affinity toward self are eliminated.

Where does peripheral tolerance occur?

In secondary lymphoid organs.

Which specific cell type plays a role in maintaining the functional balance between $Th1$ and $Th2$ lymphocytes during peripheral tolerance?

$$Tregs$$

What type of disease is Systemic Lupus Erythematosus (SLE)?

A chronic systemic inflammatory disease that affects multiple organ systems.

Which specific gene associations are strong in patients with SLE?

$HLA-DR$ or $HLA-DQ$ genes.

What is the classic dermatological sign of SLE across the nose and cheeks?

Butterfly rash.

In more than $95\%$ of lupus patients, which test is positive?

Antinuclear antibodies (ANA) test.

Which antinuclear antibody is considered lupus-specific?

Anti-ds DNA.

What are the five common patterns seen in Indirect Immunofluorescence for ANA?

Homogeneous, Rim, Speckled, Nucleolar, and Centromere.

In what percentage of lupus patients are phospholipid antibodies found?

$$60\%$$

What clinical risks are associated with phospholipid antibodies in SLE?

Deep vein and arterial thrombosis, and recurrent pregnancy loss.

How do phospholipid antibodies affect nontreponemal syphilis testing?

They can cause false-positive results.

What effect do phospholipid antibodies have on coagulation screening tests?

Prolonged $APTT$ and $PT$ times.

Which cytokine plays a key role in the inflammation that destroys bone and cartilage in Rheumatoid Arthritis (RA)?

$$TNF-\alpha$$

What is Rheumatoid factor (RF)?

An $IgM$ autoantibody that reacts with the $Fc$ portion of $IgG$.

What autoantibody is highly specific for Rheumatoid Arthritis and directed against a peptide containing modified arginine?

Anti-CCP (cyclic citrullinated peptide).

What was Granulomatosis with Polyangiitis (GPA) previously called?

Wegner’s granulomatosis.

Most patients with GPA have antibodies directed against which antigens?

Neutrophil cytoplasmic antigens such as proteinase $3$.

What is the primary pathology in Hashimoto’s thyroiditis?

Immune destruction of the thyroid gland producing hypothyroidism.

What are the laboratory results for $TSH$ and Free $T_4$ in Hashimoto’s thyroiditis?

Normal or high $TSH$ and low Free $T_4$.

What symptom of Graves’ disease involves protruding eyes?

Exophthalmos.

What are the laboratory results for $TSH$ and $FT4$ in Graves’ disease?

Low $TSH$ and high $FT4$.

In Type I Diabetes Mellitus, which cells in the pancreas are destroyed by autoantibodies?

$\beta$ cells.

Name three autoantibodies associated with Type I Diabetes Mellitus diagnosis.

Glutamic acid decarboxylase (GAD), Insulinoma antigen $2$ (IA-2), and Islet cell antibodies (ICA).

What triggers Celiac Disease and which $HLA$ types are associated with it?

Triggered by gluten; associated with $HLA-DQ2$ or $HLA-DQ8$-positive people.

Which antibody directed against tissue transglutaminase is used to screen for Celiac Disease?

$$tTG\, (IgA)$$

Type $2$ Autoimmune hepatitis (AIH-2) is positive for which antibodies?

$LKM-1$ or $LC-1$ antibodies.

The majority of patients with Primary biliary cirrhosis (PBC) produce which type of antibodies?

Mitochondrial antibodies (AMAs).

In Multiple Sclerosis (MS), most patients produce antibodies against what specific protein?

Myelin basic protein.

What finding on protein electrophoresis of cerebrospinal fluid (CSF) is characteristic of Multiple Sclerosis?

Oligoclonal bands.

In Myasthenia Gravis, autoantibodies block the binding of which neurotransmitter?

Acetylcholine (ACH).

In Goodpasture’s Syndrome, where are the target basement membranes located?

Renal glomeruli and lung alveoli.

What fluorescence pattern is seen on the glomerular basement membrane (GBM) in a kidney biopsy from a Goodpasture’s patient?

Smooth, linear, ribbon-like fluorescence.

What is the difference between primary and secondary immunodeficiencies?

Primary immunodeficiencies are inherited, while secondary immunodeficiencies are acquired due to external conditions like infection or malignancy.

In Primary Immunodeficiency, defects in $B$ cells or $Th$ cells lead to susceptibility to which types of infections?

Bacterial infections, especially sinusitis and otitis media.

What is Agammaglobulinemia?

Significantly decreased serum levels of immunoglobulins.

What causes the X-linked recessive form of Severe Combined Immunodeficiency Disease (SCID)?

$IL2RG$ gene mutation.

Purine-Nucleoside Phosphorylase (PNP) Deficiency results in a decreased number of which cells?

$T$ cells.

Wiskott-Aldrich Syndrome is characterized by which three clinical features?

Immunodeficiency, eczema, and thrombocytopenia.

What integral membrane protein is defective in Wiskott-Aldrich Syndrome?

$$CD43$$

DiGeorge Anomaly is a developmental abnormality of which embryonic structures?

Third and fourth pharyngeal pouches.

Which chromosome deletion is associated with most cases of DiGeorge Anomaly?

Chromosome $22$.

Chronic Granulomatous Disease (CGD) is caused by a defect in which enzyme system?

$NADPH$ oxidase.

Which two laboratory tests are used to detect defects in phagocytic oxidative burst?

Nitroblue tetrazolium (NBT) test and Dihydrorhodamine (DHR) assay.

Which complement deficiency is the most common?

$C2$ deficiency.

Deficiencies in late complement components ($C5-C9$) are associated with which type of infections?

Neisseria infections.