Immunity System: Questions, MCQs


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Immunity System: An Introduction

The miraculous protection mechanism in our body is called Immunity System.

Immune system keeps us healthy by preventing infections.

It defends our body against viruses, bacteria, microbes, toxins, parasites, infectious organisms and other invaders.

The study of immune system is complex, elaborated and interesting.

Our immune system is structured with special cells, proteins, tissues, and organs, that work together to defend our body against germs and microorganisms.

Troubles with the immune system can cause illness and infection, including autoimmune diseases, inflammatory diseases and cancer.

Immunology is a science which examines the organization and function of the immune system in our body.

The study of Immunology covers all aspects of the immune system, in relevance to health and diseases.

Components of the Immune System: The cells of the immune system originate in the bone marrow and most of them mature there too. After that they migrate to guard the peripheral tissues, circulating in the blood and in lymphatic system.

Antigen-Presenting Cells

  • B cells
  • Monocytes
  • Macrophages
  • Dendritic cells



Dendritic cells

Polymorphonuclear Leukocytes

  • Neutrophils
  • Eosinophils
  • Basophils
  • Mast cells




Mast cells

Cytotoxic Leukocytes

  • Natural killer cells
  • Lymphokine-activated killers

B cells
T cells

Helper T (TH) cells

Regulatory T cells

Cytotoxic T (TC) cells

NK T cells


  • IgM
  • IgG
  • IgA
  • IgD
  • IgE

Acute Phase Reactants


  • IFNs (IFN-α, IFN-β, IFN-γ)
  • TNFs (TNF-α, lymphotoxin-α, lymphotoxin-β)
  • ILs
  • Chemokines
  • TGFs
  • Hematopoietic colony-stimulating factors (CSFs)

Table Ref: Merckmanuals

Advanced studies and investigation of immunology would play a major role for the promotion of health and treatment of diseases.