Serology is the scientific study of blood serum

Blood plasma

Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

 and other bodily fluids. In practice, the term usually refers to the diagnostic

Medical diagnosis

Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...

 identification of antibodies

Antibody

An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 in the serum. Such antibodies are typically formed in response to an infection (against a given microorganism

Microorganism

A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

), against other foreign proteins (in response, for example, to a mismatched blood transfusion

Blood transfusion

Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

), or to one's own proteins (in instances of autoimmune disease

Autoimmune disease

Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to...

).

Serological tests may be performed for diagnostic purposes when an infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 is suspected, in rheumatic illnesses, and in many other situations, such as checking an individual's blood type

Blood type

A blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...

. Serology blood tests help to diagnose patients with certain immune deficiencies associated with the lack of antibodies, such as X-linked agammaglobulinemia

X-linked agammaglobulinemia

X-linked agammaglobulinemia is a rare X-linked genetic disorder that was discovered in 1952 which affects the body's ability to fight infection. XLA is an X-linked disorder, and therefore is more common in males...

. In such cases, tests for antibodies will be consistently negative.

There are several serology techniques that can be used depending on the antibodies being studied. These include: ELISA

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

, agglutination

Agglutination (biology)

Agglutination is the clumping of particles. The word agglutination comes from the Latin agglutinare, meaning "to glue."This occurs in biology in three main examples:...

, precipitation

Precipitation (chemistry)

Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...

, complement-fixation, and fluorescent antibodies

Direct fluorescent antibody

Direct fluorescent antibody is a laboratory test that uses antibodies tagged with fluorescent dye that can be used to detect the presence of microorganisms. This method offers straightforward detection of antigens using fluorescently labeled antigen-specific antibodies...

.

Some serological tests are not limited to blood serum, but can also be performed on other bodily fluids such as semen

Semen

Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

 and saliva

Saliva

Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

, which have (roughly) similar properties to serum.

Serological tests may also be used forensically

Forensics

Forensic science is the application of a broad spectrum of sciences to answer questions of interest to a legal system. This may be in relation to a crime or a civil action...

, generally to link a perpetrator to a piece of evidence (e.g., linking a rapist to a semen sample).

Serological surveys

Serological surveys are often used by epidemiologists to determine the prevalence of a disease in a population. Such surveys are sometimes performed by random, anonymous sampling from samples taken for other sexual tests.

See also

• Medical laboratory
  Medical laboratory
  A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
  
  
• Seroconversion
  Seroconversion
  Seroconversion is the development of detectable specific antibodies to microorganisms in the blood serum as a result of infection or immunization. Serology is used to determine antibody positivity...
  
  
• Serovar
• Medical technologist
  Medical technologist
  A Medical Laboratory Scientist is a healthcare professional who performs chemical, hematological, immunologic, microscopic, and bacteriological diagnostic analyses on body fluids such as blood, urine, sputum, stool, cerebrospinal fluid , peritoneal fluid, pericardial fluid, and synovial...
  
  
• Dr. Geoffrey Tovey
  Geoffrey Tovey
  Geoffrey Harold Tovey CBE CBE, MD, FRCP, FRCPath, was a doctor whose scientific contributions in the field of haematology brought him an international reputation. He was also an expert in serology and founder and Director of the UK Transplant Service.-Childhood and early life:Geoffrey Harold Tovey...
  
  , noted serologist

External links

• Serology – MedlinePlus
  MedlinePlus
  MedlinePlus is a free Web site that provides consumer health information for patients, families, and Health care providers. The site brings together information from the United States National Library of Medicine, the National Institutes of Health , other U.S. government agencies, and...
  
  Medical Encyclopedia