Biology

Human Immunity and Blood

2,096 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

A person of blood group AB can give blood to

  1. 'A' and 'B'

  2. Only 'AB'

  3. 'A', 'B' and 'O'

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A person with blood group AB has both A and B antigens on their red blood cells, but no anti-A or anti-B antibodies in their plasma. This means they can receive blood from any group (A, B, AB, or O) - they are 'universal recipients.' However, they can only donate to other AB individuals because their blood contains both antigens. Donating to A, B, or O would trigger antibody reactions in those recipients.

Multiple choice

Which of the following events is not involved in asthma?  

  1. Blocking activation of mast cells with a monoclonal antibody to IgE can give clinical benefit.

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

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

  4. Epithelial cell activation occurs.

  5. Activation of Th1cells occurs.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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

Multiple choice

Which of the following blood cells help in blood clotting?

  1. Platelets

  2. Red blood cells

  3. White blood cells

  4. None of these

  5. NA
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Platelets, also known as thrombocytes, are involved in blood clotting. They adhere to the damaged blood vessels and thromboplastin is liberated from an injured tissue. Hence, it is the correct answer.

Multiple choice

Superantigens are toxins produced by many pathogenic bacteria and viruses. Which of the following statements regarding superantigens is FALSE?

  1. Staphylococcal toxic shock syndrome is an example of superantigen associated disease.

  2. Superantigen associated diseases are characterized by markedly elevated circulating levels of pro-inflammatory cytokines.

  3. In humans, a superantigen reacts with approximately 1 in 50 T-cells.

  4. Superantigens activate large numbers of B-cells.

  5. The first bacterial SAg was isolated by Bergdoll.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Superantigens simultaneously activate large numbers of T-cells carrying a particular T-cell receptor Vβ gene, by binding at a site distinct from the antigen-binding groove. Since there are 50 different Vβ genes in humans, a superantigen will react with approximately 1 : 50 T-cells in contrast to a conventional peptide antigen that will react with 1 : 104 to 1 : 108 T-cells. They do not react with the BCR.

Multiple choice

Mycobacterium is a genus characterized by various pathogenic bacteria. Granuloma formation in mycobacterial infection does NOT include which of the following processes?

  1. Engulfment of the mycobacteria by the macrophages

  2. Replication of the mycobacteria within the phagosomes

  3. Production of IL-12 to drive Th1 differentiation of immature CD4 cells

  4. TNF-α production for activation of macrophages to epithelioid forms

  5. Production of IL-4
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Production of IL-4 by Th2 cells is not a part of granuloma formation, which involves Th1 activation rather than Th2 activation.

Multiple choice

An antigen is a substance which provokes an adaptive immune response. Which type of cell is known to be involved in the initial presentation of antigen to T lymphocytes?

  1. Plasma cells

  2. Dendritic cells

  3. Neutrophil polymorphonuclear leucocytes

  4. Erythrocytes

  5. Platelets
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Dendritic cells (DCs) are antigen-presenting cells (also known as accessory cells) of the mammalian immune system. There are several types of dendritic cells, well distributed over the body.

Multiple choice

The cells responsible for antigen specific humoral responses in humans are the ___________.

  1. neutrophil polymorphonuclear leucocytes

  2. microglial cells

  3. macrophages

  4. Kupffer cells

  5. B lymphocytes
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

B lymphocytes secrete antibodies and cytokines and are responsible for antigen specific humoral responses. They can process and digest antigens particularly in secondary immune responses but do not have a major phagocytic role.

Multiple choice

Which among the following can be excluded from the mononuclear phagocyte system of the body?

  1. Monocytes

  2. Kupffer cells

  3. Lymph node medullary macrophages

  4. Endothelial cells

  5. Kidney mesangial cells
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Endothelial cells are not essentially phagocytic although they do contribute by the production of mediators of the inflammatory process, particularly acute inflammation and were previously lumped together with the mononuclear phagocyte system in what was known as the reticuloendothelial system (RES).