The main difference between Gamma globulin and immunoglobulin is that gamma globulin includes IgA, IgM, IgD, IgE, and IgG, whereas immunoglobulin is a Y-shaped protein used by the immune system to identify and neutralize foreign objects like pathogenic bacteria and viruses.
Gamma globulin and immunoglobulin are two glycoprotein molecules produced by the plasma cells. They help in the immune response by specifically recognizing and binding to particular antigens like bacteria or viruses and aid in their destruction. However, not all gamma globulins are immunoglobulins.
Key Areas Covered
- What is Gamma Globulin
- Definition, Characteristics, Importance
- What is Immunoglobulin
- Definition, Characteristics, Importance
- Similarities Between Globulin and Immunoglobulin
- Outline of Common Features
- Difference Between Globulin and Immunoglobulin
- Comparison of Key Differences
Key Terms
Gamma Globulin, Immunoglobulin
What is Gamma Globulin
Gamma globulin is a class of globulins and a globular protein family identified by their position in serum protein electrophoresis. Immunoglobulins are the most significant gamma globulins. Therefore, IgA, IgM, IgD, IgE, and IgG are gamma globulins.
Figure 1: Serum Protein Electrophoresis
IgA
Immunoglobulin A is an antibody that plays a role in the immune function of mucous membranes. The amount of IgA in the mucosal membranes is greater than in other antibodies. IgA has two subclasses (IgA1 and IgA2) and it can be also produced in monomeric as well as dimeric forms. The most prevalent form of IgA is the dimeric form and another name for it is the secretory IgA (sIgA). The sIgA is the main immunoglobulin that occurs in mucous secretions, including tears, saliva, sweat, colostrum, and secretions from the genitourinary tract, gastrointestinal tract, prostate, and respiratory epithelium. Immunoglobulin A is also found in small amounts in the blood.
IgM
Immunoglobulin M is the largest and the first antibody to appear in response to initial exposure to an antigen. The main source for specific IgM production is the plasmablasts residing in the spleen. On the other hand, IgM has three functions in the body. It can bind complement component C1 and activate the classical pathway, leading to the opsonization of antigens and cytolysis. In addition, IgM binds to the poly-immunoglobulin receptor (pIgR) and comes to IgM to mucosal surfaces, such as the gut lumen, and into breast milk. Further, the binding of IgM to Fc receptors can mediate endocytosis while it represents the mucosal immunity in the gut.
IgG
Immunoglobulin G is an antibody representing 75% of the serum antibody. Therefore, it is the most common type of antibody in blood circulation. Moreover, plasma B cells produce and secrete IgG. On the other hand, IgG is the major component of humoral immunity and controls infections in the tissues. However, IgG binds pathogens such as bacteria, viruses, and fungi to prevent infections of the body. This causes the immobilization and binding together in agglutination. Normally, the IgG coating of pathogen surfaces or opsonization allows their recognition and ingestion by phagocytic immune cells, which causes the pathogen to eliminate itself. It also activates the classical pathway of the complement system. In addition, it binds to toxins to neutralize them.
IgD
Immunoglobulin D is the type of immunoglobulin that makes up 1% of proteins in the plasma membrane of immature B-lymphocytes. IgM is co-expressed with IgD. The blood serum contains IgD in small amounts. Usually, it represents 0.25% of the serum immunoglobulins. It is a monomeric antibody. Generally, IgD signals B cells to activate. After activation, B cells are ready to take part in the defense of the body as part of the immune system. IgD starts to express when the B cell exits the bone marrow to populate peripheral lymphoid tissues. Furthermore, IgD binds to basophils and mast cells and activates these cells to produce antimicrobial factors to participate in respiratory immune defense.
IgE
Immunoglobulin E is an immunoglobulin that only occurs in mammals. Plasma cells synthesize IgE. It is expressed in the monomeric form. Significantly, IgE can raise immune responses against parasitic warms and protozoan parasites. In addition, IgE is involved in type I hypersensitivity, which manifests in various allergic conditions such as allergic asthma, most types of sinusitis, allergic rhinitis, food allergies, and specific types of chronic urticaria and atopic dermatitis. Being the least abundant immunoglobulin in the serum, it accounts for 0.05% of the serum immunoglobulins.
What is an Immunoglobulin
Immunoglobulins, also known as antibodies, are glycoprotein molecules produced by plasma cells. Their function is to recognize and bind to particular antigens including bacteria, viruses, and other pathogens, and to help recognize them by the cells of the immune system. This plays a critical role in immunity. Although the antibody immune response is specific, it is highly complex.
Figure 2: Immunoglobulins
Furthermore, immunoglobulin contains five subclasses (isotypes): IgA, IgD, IgE, IgG, and IgM. They differ in their biological features, structure, target specificity, and distribution. Therefore, the assessment of the immunoglobulin isotype can give useful insight into the complex humoral immune response. Knowledge of immunoglobulin structure and classes is also important for the selection and preparation of antibodies as tools for immunoassays and other detection applications.
Similarities Between Gamma Globulin and Immunoglobulin
- Gamma globulin and immunoglobulin are two classes of globular proteins.
- They play a critical role in immunity to bind and recognize pathogens.
Difference Between Gamma Globulin and Immunoglobulin
Definition
Gamma globulin refers to a class of globulins, identified by their position after serum protein electrophoresis, while immunoglobulin refers to a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses.
Significance
Usually, immunoglobulins are a type of gamma globulins while immunoglobulins are Y-shaped globulins.
Function
Gamma globulin is important in injections to boost one’s immunity while immunoglobulin helps in the immunity to recognize pathogens.
Conclusion
In brief, gamma globulin is a class of globulin proteins and immunoglobulins are the most prominent type of gamma globulins. In contrast, immunoglobulin is a Y-shaped globulin with a vital role in the recognition of pathogens in the immune system. IgA, IgE, IgD, IgG, ad IgM are five types of immunoglobulins. However, gamma globulin is given in injections to boost immunity. Therefore, the main difference between gamma globulin and immunoglobulin is their function.
References:
- Justiz Vaillant AA, Jamal Z, Ramphul K. Immunoglobulin. [Updated 2022 Jul 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.
- Gamma-Globulins. Gamma-Globulins – an overview | ScienceDirect Topics. (n.d.). Retrieved September 9, 2022.
Image Courtesy:
- “Electrophoresis” By Jfdwolff – Own Work (Public Domain) via Commons Wikimedia
- “Mono-und-Polymere” By Martin Brändli (brandlee86) – Own Work (CC By-SA 2.5) via Commons Wikimedia
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