Question

Explain breifly or give the description of the human Immune response.

Answer 1

Humoral Immune response:

Activation Phase:

• This phase begins when an invading bacteria is phagocytized by an antigen presenting cell (APC).
• The lysosome containing digestive enzymes combines with the phagosome to process the antigens.
• The processed antigens combine with the MHC class II proteins and are presented on the surface of the APC.
• The Helper T cell i.e., CD4+ recognize the displayes antigen on the APC and bind to the MHC class II antigenic peptide complex.
• This binding triggers the APC to release the cytokine IL-1, which activates the helper T cell.
• The activated T helper cells release the cytokine IL-2, which stimulates the cell to proliferate.
• Later on produces many helper T cells, each with a receptor specific for the original processed antigen.

Effector Phase:

• This phase begins when a B cell that exhibits on its surface an IgM receptor specific for the same antigen originally engulfed by the APC encounters and binds the antigen.
• Then the B cell engulfs the complex by receptor-mediated endocytosis. The phagosome containing the antigen fuses with a lysosome. 
• The antigen is processed.
• The processed antigen then binds the MHC class II protein and is displayed on hte same surface of the B cell.
• The Helper T cells now bind to the displayed antigen on hte surface of the B cell causing the helper T cell to release cytokines.
• Then the cytokines stimulate  the B cell to divide and proliferate into identicsl B cell copies.
• The plasma cells release antibodies with a specificity identical to that of the surface receptors on the parent B cell.
• These carry out the ultimate goal of fighting the foreign invaders.
• The released antibodies bind in a lock- and key- fashion to the antigen on the surface of the original bacterial invaders.
• This makes it easier for killer cells to attack and destroy the bacteria by phagocytosis and the release of proteins cause the direct lyses of the bacteria.
• Simultaneously, a blood component known as complement is signaled to attack and puncture holes in the bacteria.

 

 

 

 

 

 

Immune response:

• The immune response is a reaction that occurs within an organism for the purpose of defending against the foreign invaders.
• The 3 parts of the immune response are WBC, antibodies and the complement system.