Biology

Human Immunity and Blood

2,051 Questions

Human immunity and blood questions cover the physiological mechanisms protecting the body against diseases and the components of blood. Topics include blood groups, cell mediated immunity, monoclonal antibodies, and blood coagulation. These biology topics frequently appear in general science sections of competitive exams.

Blood groupsCell mediated immunityMonoclonal antibodiesBlood coagulationCancer immunology

Human Immunity and Blood Questions

Multiple choice

Which of the following mice strains are deficient in NK cells?

  1. SJL

  2. Beige

  3. Nude

  4. MRL-lpr/lpr

  5. Moth-eaten viable
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

NK cells are spontaneously cytotoxic for certain tumor cell lines and express CD16, the low affinity Fc gamma RIII. Beige mice congenitally lack NK cells and die with spontaneous tumors earlier than their non-deficient heterozygous+/bg littermates.

Multiple choice

Which of the following mast cell products is not preformed and therefore has to be newly synthesised?

  1. Histamine

  2. Prostaglandin D2

  3. Heparin

  4. Neutral protease

  5. Eosinophil chemotactic factor (ECF)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Prostaglandins and thromboxanes are newly synthesised by the mast cell using the cyclo-oxygenase pathway. The leukotrienes B4, C4 and D4 (slow reacting substance of anaphylaxis, SRS-A) are also newly synthesised by the mast cell, in this instance using the lipoxygenase pathway.

Multiple choice

Which of the following can block the Type I hypersensitivity?

  1. Histamine

  2. An IgA myeloma

  3. A myeloma protein of mixed antibody class

  4. Sodium cromoglycate

  5. Interleukin-5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium cromoglycate is a mast cell stabiliser,  which makes the cell resistant to triggering. It is thus able to block type I hypersensitivity.

Multiple choice

Which of the following diagnostic markers is for intestinal tumor?

  1. Alpha-fetoprotein

  2. Carcinoembryonic antigen

  3. The presence of Reed-Sternberg cells

  4. EBV-related antigens

  5. Common acute lymphoblastic leukemia antigen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carcinoembryonic antigen (CEA) is an oncofetal antigen but there is a high incidence of false positives. Reappearance of CEA after surgical removal of the primary tumor is strongly indicative of fresh tumor growth.

Multiple choice

Which of the following cannot bypass the T-helpers?

  1. Failure of regulatory T-cells

  2. Polyclonal activation of B-cells

  3. Idiotypic mechanisms

  4. Antigenic cross-reaction

  5. T-cell recognition of carrier complexed to autoantigen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Failure of regulatory T-cells would release the T-helper for direct stimulation by antigen. This statement is therefore incorrect, since this would not be a bypass of the T-helpers.

Multiple choice

The antibodies produced by lymphocytes in vertebrates are the type of ______ proteins.

  1. Nutrient and Storage Proteins

  2. Defence Proteins

  3. Receptor Proteins

  4. Exotic Proteins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

They are protective proteins which protect the body from ill effects of poisonous (toxic) substances and pathogenic invaders (virus, bacteria and other pathogens) by destroying the toxins and invaders. Important defence proteins are antibodies or immuno-globulins produced by lymphocytes in vertebrates. Interferon protects cells from the attack of viruses. Thrombin and fibrinogen form blood clots to prevent loss of blood and infection at sites of injuries. Certain proteins, called exploitive proteins, are normally toxic, but they may play a defensive role under certain conditions.

Multiple choice

Type IV hypersensitivity is a cell-mediated immune reaction. Which of the following is true regarding the type IV hypersensitivity?

  1. Specific antibodies are directed against cellular targets.

  2. Complement is involved.

  3. Mast cells play a central role in the effector component.

  4. Th1 cells play a central role in the effector component.

  5. Histology is typically granulomatous.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

T cells are involved; the principle effector cells are Th1, secreting interferon-gamma and TNF, resulting in activation of macrophages. Th17 cells may also play a role.

Multiple choice

Which of the following statements is true regarding the removal of cells by apoptosis?  

  1. Auto-antigens are frequently methylated and this results directly in autoimmune sensitisation.

  2. C5 plays a central role in cellular clearance.

  3. Apoptosis can also be mediated by T cells using FAS:FAS ligand interactions.

  4. Nuclear material is expanded beneath a blebbed membrane.

  5. Macrophages secrete the pro-inflammatory cytokines IL-10 and TGFβ in response to cellular ingestion.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

FAS ligand (CD178) is expressed on activated T cells; the interaction with FAS, a protein on many cell types triggers enzymes to degrade the target cell DNA.

Multiple choice

Which of the following concerning diseases involving immunological mechanisms of type II hypersensitivity is CORRECT?    

  1. Type II hypersensitivity involves circulating or tissue-bound immune complexes.

  2. Inflammation occurs within minutes.

  3. May alter the cell metabolism through receptor dysfunction.

  4. Are responsible for lupus nephritis.

  5. Are largely Th1 cytokine dependent.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Grave's disease results from the binding of specific antibodies to cell-bound antigen, TSH receptor. Activates this receptor and stimulates the thyroid cell to produce thyroid hormone as a result.

Multiple choice

Which of the following is not included in the serological findings in patients with systemic lupus erythematosus (SLE)?

  1. Raised serum IgG levels

  2. Antibodies to double-stranded DNA

  3. Decreased C3 and C4 levels

  4. A positive lupus anticoagulant

  5. Antibodies to cyclic citrullinated peptide (anti-CCP antibodies)
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Anti-CCP antibodies are found in >96% of patients with RA and not in other inflammatory conditions, making this assay specific for RA and therefore useful in clinical practice.

Multiple choice

Th cells are a type of T cell that play an important role in the immune system. Which of the following statements about Th responses is FALSE?  

  1. Th2 cells produce cytokines that favour the production of IgE.

  2. Th1 cells can be found in atopic eczema lesions.

  3. Th2 cells characteristically express the foxp3 gene product.

  4. Th2 cells produce IL-4.

  5. Th1 cells are associated with the transcription factor T-bet.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Foxp3 is a protein involved in immune system responses. It is associated with regulatory T cells.

Multiple choice

Which of the following statements is NOT thought to be involved in asthma?  

  1. Activation of Th1cells.

  2. Epithelial cell activation occurs.

  3. Upregulation of VCAM-1 results in infiltration of eosinophils.

  4. Adrenaline is always used to reverse bronchoconstriction in mild asthmatics.

  5. Blocking activation of mast cells with a monoclonal antibody to IgE can give clinical benefit.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Adrenaline is only used in status asthmaticus and never in mild asthma.