WHAT IS BLOOD SERUM? - MEDICINE - 2025

The serum is a blood component characterized by the absence of RBCs, WBCs or coagulants. It is defined as the plasma included in the blood that does not include any type of fibrinogen or proteins produced by the liver for blood clotting.

In synthesis, blood serum is defined as the combination of all proteins, electrolytes, antibodies, antigens, hormones, and exogenous substances that do not contribute to the blood clotting process.

Blood serum (serum)

The appearance of blood serum is characterized by being yellowish and liquid. This liquid is mostly an aqueous medium frequently used for in vitro cell development due to the high concentration of hormones, nutrients and non-coagulant proteins present in it.

One of the most commonly used blood sera for eukaryotic cell growth in vitro is Fetal Bovine Serum or SFB (Rhoades & Bell, 2009).

Serum is the most widely used blood component to check different blood groups and diagnose certain diseases and levels of nutrients and hormones necessary for the proper functioning of the body.

The science that is responsible for the study and treatment of blood serum is known as serology.

Serology

Serology is a branch of medical sciences in charge of studying blood serum in order to detect the presence of antibodies produced by the body to fight an infection.

The serology test is carried out by taking a blood sample from the veins - usually from the flexure of the elbow or the front of the elbow. To take this sample, the skin must be free of germs and the space must have excellent hygiene conditions.

The sample is taken with a needle directly from inside the vein through which the blood passes and is collected in a tube attached to the needle.

Serology analyzes the blood sample to determine how certain antibodies react to the presence of antigens. In this way, it is possible to determine whether or not there is the presence of microorganisms responsible for an infection in the body.

Serological analysis

Among the most common techniques used by serology we find agglutination, precipitation, and complement fixation, among others (ADAM, 2009).

• Agglutination Analysis: exposes antibodies present in the body to specific antigens to determine whether or not they agglutinate.

• Precipitation analysis: measures the similarity of different antigens based on the presence of antibodies in body fluids.

• Complement fixation: it is an immunological test used to determine the presence of antibodies that, when mixed with antigens, can react, denoting the presence of an infection.

Serological process of complement fixation (Acharya, 2015)

Result of serology

The results of a serological test can indicate the presence of antibodies in the body in order to detect the presence of an infection.

Normal results are characterized by the absence of antibodies, while abnormal results show that there is a response by the immune system to the presence of a microorganism or antigen (O'Connell, 2015).

Serological analysis can indicate the existence of a disorder in the autoimmune system as long as the presence of antibodies fighting normal proteins and antigens of the body is detected.

Some of the infections that can be detected in blood serum are:

• Amebiasis

• Brucellosis

• Acquired Immunodeficiency Virus (HIV)

• Fungi

• Measles

• Rubella

• Syphilis

• Viral hepatitis (various types)

Differences between plasma and blood serum

Both serum and plasma are blood components that are often confused because their appearance is similar.

While serum does not include any type of fibrinogen, plasma is partially made up of these coagulant proteins and other types of cells and blood components such as red blood cells, white blood cells, LDL, HDL, transferrin and prothrombin. (Wilkin & Brainard, 2015)

Both plasma and serum are components of blood that are often used for blood testing. Each of these components is made up of hormones, glucose, electrolytes, antibodies, antigens, nutrients, and other particles.

However, what radically differentiates these two blood components is the presence of clotting agents. It can be said that blood serum is equal to plasma removing any type of coagulant agent (HAYAT, 2012).

Differences between plasma and blood serum (Medical-Labs, 2014)

Fetal bovine serum

Fetal bovine serum is a type of blood serum from the blood of the cow fetus, commonly used for the culture of eukaryotic cells in vitro thanks to its high content of hormones and nutrients and the low levels of antibodies present in it.

This type of blood serum is composed of hormones and accelerated growth factors that allow it to be an effective medium for the culture of human cells and tissues with different metabolic demands.

Currently, there is much controversy around the extraction of this type of blood serum, since it must be taken from the fetus of the pregnant mother cow at the time of its execution in the slaughterhouse.

Despite ethical questions on this issue, bovine blood serum remains one of the most commonly used aqueous media for human cell culture in the world.

It is estimated that 500,000 liters of fetal bovine serum are produced annually in the world, equivalent to the extraction of one million fetuses per year.

Risks associated with the use of fetal bovine serum

There are some reasons why fetal bovine serum should not be used in the field of scientific research (Even, Sandusky, & Barnard, 2006):

-The fetal bovine serum may contain contaminants that once present in the solution are impossible to remove from the cell culture.

-Many substances present in bovine blood serum have not yet been identified.

-The composition of fetal bovine serum can alter with the phenotypic and genotypic stability of the cell culture, affecting the final results.

-Serum can suppress cell development which can affect cell growth, especially when it comes to organ culture and growth.

References

1. ADAM, I. (1 of 12 of 2009). New York Times Health Guide. Obtained from New York Times Health Guide.
2. Acharya, A. (5 of 5 of 2015). Microbe Online. Obtained from Complement Fixation Test: Principle, Procedure and Results.
3. Even, M., Sandusky, C., & Barnard, N. (2006). Serum-free hybridoma culture: ethical, scientific and safety considerations. TRENDS in Biotechnology Vol.24 No.3, 105-106.
4. HAYAT, K. (3 of 7 of 2012). MEDIMOONTrusted Medical Site. Obtained from Difference Between Plasma And Serum.
5. Medical-Labs. (2014). Medical-Labs. Obtained from Difference Between Plasma and Serum.
6. O'Connell, K. (8 of 12 of 2015). Health Line. Obtained from What is a Serology.
7. Rhoades, R., & Bell, D. (2009). Chapter 9 - Blood Components. In R. Rhoades, & DR Bell, Medical Physiology: Principles for Clinical Medicine (p. 171). Baltimore, MD: lippincott williams & wilkins.
8. Wilkin, D., & Brainard, J. (2015). Blood. In D. Wilkin, & J. Brainard, Human Biology (p. 109). flexbook.