Question

1. What is responsible for determining whether a response is humoral or cell-mediated?
2. What makes IgA antibody different from IgG?
3. What is the basic difference between humoral immunity and cellular immunity?

Answer 1

1.The cellular interactions between lymphocytes responsible for determining whether antigen induces a cell mediated or humoral response. The humoral response or antibody response-mediated response involves B cells that recognise antigens or pathogens that are circulating in the lymph or blood. The cell -mediated response involves mostly T cells are responds to any cell that display aberrant MHC markers,including cells invaded by pathogens,tumor cells or transplanted cells.

2 .IgA and IgG are antibodies.Approximately 75 percentage of serum antibodies in human.Antibodies are proteins made by the immune system to fight antigens. IgA means Immunoglobulin A .IgA antibodies are found in the mucous membrane of the lungs ,sinuses,stomach and intestines.It is found small amounts in blood.The secreatory compound of IgA protects from immunoglobulin from being degraded by proteolytic enzymes.Thus IgA can survive in the harsh gastrointestinal tract and provide protection against microbes..It can also inhibit the inflammatory effects of other immunoglobulin.

IgG antibodies are found in all body fluids.Each IgG antigen has two antigen binding sites.It is a class of immunoglobulins that facilitate the phagocytic destruction of microorganisms to the body.High IgG means a long term intection such as HIV or multiple myeloma,lomg term hepatitis etc.

The normal range of IgG in adults is 6.0-16.0g/L and IgA is 0.8-3.0g/L.

3.Humoral immunity and cell mediated immunity are two types of adaptive immunity in which a specific immune response is produced for a particular response.

Humoral immunity is mediated by macromolecules found in extracellular fluids such as secreated antibodies,complement proteins and in certain antimicrobial peptides.It is the formation of antibodies against foreign antigens and triggers specific destructive mechanisms against invading pathogens.

Cell mediated immunity is an immune response that doesnot involve antibodies.T- cells are responsible for cell mediated immunity.It involves the destruction of body cells that are infected with pathogens or have become damaged or cancerous.