Question

How innate immune reactions stimulate adaptive immune responses

1. What are examples of PAMPs and DAMPs recognized by the innate immune system? What is the outcome of recognition?

Answer 1

1. How innate immune reactions stimulate adaptive immune responses

The term immunity has been traditionally referred to the resistance exhibited by the host towards injury caused by microorganisms and their products.

Innate immunity is the resistance to the infection that an individual possesses by virtue of his or her genetic and constitutional make up. The resistance that an individual acquires during life is known as acquired immunity. Acquired immunity is of two types, active and passive. Active immunity is the resistance developed by an individual as a result of an antigenic stimulus. It is also known as adaptive immunity as it represents the adaptive response of the host to a specific pathogen or other antigen.

Adaptive immune system activated when an innate immune response is insufficient to control an infection against a microorganism. The adaptive immune system activated according to the stimulus from innate immune system. Innate immune responses stimulate adaptive immune responses. Innate immune system contains specific cells called antigen presenting cell ( APC) which detect the foreign bodies or harmful antigens. This cells inform the adaptive immune system about potentially harmful antigens and stimulate adaptive immune system for the immune response. Adaptive immune system are of two types, cell mediated (T cells involved ) and humoral (B cell controlled) . Both T cells and B cells are inactive in the absence of an information from APCs. Dentritic cells, macrophages, B cells before activation and differentiation etc are act as APCs. APCs phagocyte the microorganisms and carry antigenic fragments called epitopes at the surface and stimulate adaptive system to a response.

2. What are examples of PAMPs and DAMPs recognized by the innate immune system?

PAMPS

Pathogen Assisted Molecular Patterns are unique molecules which only present in the microorganisms not in the human cells.They are the microbial molecules. They initiate and perpetuate infectious pathogen induced inflammatory response.

Eg: Lipopolysaccharide from the outer membrane of gram negative bacteria, bacterial lipoprotiens and lipopeptides, porins in the outer membrane of the gram negative cell wall, peptidiglycans, lipoteichoic acid, flagellin, bacterial and viral nucleic acid, double stranded viral DNA.

DAMPS

Damage Associated Molecular Patterns are host cell molecules or endogenous molecule released from damaged or dying cells and activate the innate immune system by interacting with Pattern Recognition Receptors. They initiate and perpetuate noninflammatory immune responses.

Eg: Heat shock proteins, altered membrane phospholipid, ATP RNA DNA, spill out of damaged cells.

3.What is the outcome of recognition?

To recognize PAMPS body cells have receptors called pattern recognition receptors like macrophages, dendritic cells, endothelial cells, mucosal endothelial cells, and lymphocytes. PAMPS activate innate immune response and protecting the host from infection. DAMS released from damaged cells and they activate the innate immune system by interacting with Pattern Recognition Receptors. They initiate and perpetuate noninflammatory immune responses.

Eg: Formyl peptides(PAMPS) and Mitochondrial Formyl Receptor( DAMPS) together leads to inflammation and cell damage.

Here the receptors are Formyl peptide receptor 1 (FPR1) and Toll Like Receptor 9.