Immune terms

Microscopic organisms which reside in water, soil and air. ... Some microbes are pathogenic, others are important for our health- commensal.

Any substance that is able to cause an immune response in the body. Reacts specifically with the resultant antibodies and/or cells generated

A type of protein that impacts the immune system by either ramping it up or slowing it down. Cytokines can occur naturally in the body or be produced in a laboratory

Special proteins created by white blood cells (activated B cells) that can kill or weaken infection-causing organisms. Antibodies travel through the blood stream looking for specific pathogens. The body can create new antibodies in response to new pathogens or vaccines. Also referred to as immunoglobulin (Ig).

2 forms: Secretory IgA is found in the linings of the respiratory tract & digestive system, saliva, tears, and breast milk (colostrum). Known as the antiseptic paint of mucous membranes. Can activate the complement system in the presence of lysosome to kill certain organisms. Serum IgA cannot activate complement system.

Found in blood in low levels; cannot activate the complement system. Approximately half of antigen specific receptors on B lymphocyte membranes are composed of IgD antibodies

Found in serum- small amounts. Most IgE is attached to mast cells & basophils (granulocytes). High levels of IgE found on those with allergies (e.g asthma/hayfever)

Most common antibody in blood/tissue fluid (75%) of total serum immunoglobin level. Defends against diffusing toxins and spreading microbes, IgG response found mainly to occur in the secondary immune response. Effective opsonins.
Maternal IgG is transferred across placenta, giving passive protection to new borns for 4-6/12)

Largest of the immunoglobulin molecules; usually earliest antibody response in a primary immune response; short lived.

Phagocytes eat up pathogens by attaching to and wrapping around the pathogen to engulf it. Once the pathogen is trapped inside the phagocyte, it is in a compartment called a phagosome. The phagosome will then merge with a lysosome or granule to form a phagolysosome, where the pathogen is killed by toxic materials, such as antimicrobial agents, enzymes, nitrogen oxides or other proteins.

Large molecules composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.

Substances present in serum which promote phagocytosis of bacteria (act as ‘markers’).

The capacity of antibodies and complement components (as well as other proteins) to coat dangerous antigens that can then be recognized by antibodies or complement receptors on phagocytic cells. ... The opsonins act as markers or tags that allow recognition by the immune system of the body

Phagocytosis, process by which certain living cells called phagocytes ingest or engulf other cells or particles.

A type of cell death in which a series of molecular steps in a cell lead to its death. This is one method the body uses to get rid of unneeded or abnormal cells. The process of apoptosis may be blocked in cancer cells.

Cells which process protein antigens into peptides- these can then be presented to T cell receptors on the cell surface.

Part of innate immune system response, playing an important role in host defence and inflammation. The complement system consists of a group of protein molecules found circulating in the blood stream & body tissues (humoral), which activate each other rapidly in a sequential cascade. This results in lysis of foreign and infected cells, phagocytosis of foreign particles and cell debris and inflammation of surrounding tissue.

A type of white blood cell (WBC)