Immune System 101

The dendritic cell’s job is to take the foreign object and process its proteins (the building blocks that make up the object) into small chunks. The dendritic cells then present those chunks (called antigens) on their surface. T cells, adaptive immune cells that help fight infection by activating other immune cells and killing infected cells, can interact with the dendritic cell and bind the surface antigen it presents. T cells are only activated by specific antigens (there specific T cells for each different antigen). An activated T cell will release small proteins (cytokines, blue and green dots above) that help speed up the immune response and bring inflammation to the site of infection (swelling, redness, heat, pain, etc). The other major adaptive immune cell type, B cells, are similar in that each cell is specific to a single antigen. B cells produce antibodies that help stop foreign objects from spreading in the body. They also produce memory cells which help the body remember the foreign threat and helps to speed up the process of immune reaction. The adaptive immune response is slower and requires 10-14 days to reach peak response.

The innate immune response is the first line of protection against foreign objects in the human body. Before a pathogen can even get inside us, our hair, mucous membranes (in the eyes, nose, mouth, etc), and airway reflexes (coughing, salivation) work to prevent it from getting further. Once a foreign object enters the body, a specialized cell type called a dendritic cell will engulf the object and break it down. The innate immune response is fast-acting– it takes only 1-3 days to initiate an immune response.

Definitions

Antibodies: A blood protein that binds and counteracts a specific antigen. Antibodies combine chemically with substances that the body recognizes as foreign.

Antigen: Any substance that causes your immune system to produce antibodies against it

Cytokines: small proteins that have an effect on other cells

Dendritic cells (DCs): Antigen-presenting cells (APCs) in the immune system. Their main function is to process the antigen and present part of it on the cell surface to show the T cells of the immune system. They act as messengers between the innate and the adaptive immune systems

Pathogen: a microorganism that can cause disease