Question

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1. Define each type of immunity. Name one type of cell involved in each of the following processes and where the cell is found: a. Innate immunity: b. Adaptive immunity 2. Watch the video on slide 3 and answer the following. a. How do B cells react to antigens? b. Which cells regulate the immune system? c. Which adaptive immune cells kill virus-infected cells? 3. What is the purpose of humoral immunity?

Answer 1

1.a. Innate immunity

It is a general nonspecific defence mechanism consisting of physical, chemical and cellular defences against pathogens that come into play immediately after an antigen's appearance in the body.

Type of cell involved,

Phagocytic cells which include macrophages and neutrophils. Phagocytes are found in the blood stream.

b.Adaptive immunity

• Adaptive immunity (acquired immunity) is an immunity that occurs after exposure to an antigen, either from vaccination or from a pathogen. Type of cell involved
• Lymphocytes - Either T cells or B cells. They occur in the blood and lymph. It develops in the thymus and bone marrow. 2. The antigen recognition molecules of B cells are the immunoglobulins or Ig. It has B cell receptor (BCR) on their surface, it is used to bind a specific protein(antigen) . When B cells bind to antigen, they release antibodies that stick to the antigen and prevent it from harming the body.
• B cells secrete cytokines to attract other immune cells. b. Regulatory T cells(Treg) and T helper cells (Th) have a role in regulating other cells in the immune system.
• C. Helper T cells can recognise virus infected cells and produce cytokines. Cytotoxic T lymphocytes, natural killer cells and antiviral macrophages can recognise and kill virus infected cells.
• 3.Humoral immune system protects the extracellular space, that is antigens from pathogens outside the infected cells. In this antibodies produced by B cells cause destruction of extracellular micro organisms and prevent infections. It is achieved by neutralising them or phagocytosis.