Cross-reactivity
Encyclopedia
Cross-reactivity is the reaction between an antibody
and an antigen
that differs from the immunogen
. It is sometimes also referred to as crossimmunity or cross-protective immunity. A few examples of cross-reactivity have been confirmed in humans, one of which involves influenza virus
-specific CD8+
T cell
and hepatitis C virus
antigens.
An adaptive immune response
is specific to the antigen that stimulated it (called the immunogen). However, many naturally occurring 'antigens' are a mixture of macromolecule
s (e.g. from pathogen
s, toxin
s, protein
s, pollen
) comprising several epitope
s. Contact with a complex antigen such as a virus
will stimulate multiple immune responses
to the virus' different macromolecules as well as the individual epitopes of each macromolecule. For example, the tetanus
toxin is a single protein macromolecular antigen but will stimulate many immune responses due to the tertiary structure of the protein yielding many different epitopes.
Medicinal uses for this idea include immunization
to bacterial infection
s. The toxin
that creates the immune response will have an epitope on it that stimulates the response. Denaturing
the protein may 'disarm' its function but allow the immune system to have an immune response thus creating an immunity without harming the patient.
Cross-reactivity is also a commonly evaluated parameter for the validation of immune and protein binding based assay
s such as ELISA
and RIA
. In this case it is normally quantified by comparing the assays response to a range of similar analytes and expressed as a percentage. In practice, calibration curve
s are produced using fixed concentration ranges for a selection of related compounds and the mid-points (IC50
) of the calibration curves are calculated and compared. The figure then provides an estimate of the response of the assay to possible interfering compounds relative to the target analyte.
and banana
.
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...
and an antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
that differs from the immunogen
Immunogenicity
Immunogenicity is the ability of a particular substance, such as an antigen or epitope, to provoke an immune response in the body of a human or animal.- Immunogenicity :The ability to induce humoral and/or cell-mediated immune responses....
. It is sometimes also referred to as crossimmunity or cross-protective immunity. A few examples of cross-reactivity have been confirmed in humans, one of which involves influenza virus
Orthomyxoviridae
The Orthomyxoviridae are a family of RNA viruses that includes five genera: Influenzavirus A, Influenzavirus B, Influenzavirus C, Isavirus and Thogotovirus. A sixth has recently been described...
-specific CD8+
CD8
CD8 is a transmembrane glycoprotein that serves as a co-receptor for the T cell receptor . Like the TCR, CD8 binds to a major histocompatibility complex molecule, but is specific for the class I MHC protein. There are two isoforms of the protein, alpha and beta, each encoded by a different gene...
T cell
T cell
T cells or T lymphocytes belong to a group of white blood cells known as lymphocytes, and play a central role in cell-mediated immunity. They can be distinguished from other lymphocytes, such as B cells and natural killer cells , by the presence of a T cell receptor on the cell surface. They are...
and hepatitis C virus
Hepatitis C virus
Hepatitis C virus is a small , enveloped, positive-sense single-stranded RNA virus of the family Flaviviridae...
antigens.
An adaptive immune response
Adaptive immune system
The adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth. Thought to have arisen in the first jawed vertebrates, the adaptive or "specific" immune system is activated by the “non-specific” and evolutionarily older innate...
is specific to the antigen that stimulated it (called the immunogen). However, many naturally occurring 'antigens' are a mixture of macromolecule
Macromolecule
A macromolecule is a very large molecule commonly created by some form of polymerization. In biochemistry, the term is applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles...
s (e.g. from pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s, toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s, protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
) comprising several epitope
Epitope
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The part of an antibody that recognizes the epitope is called a paratope...
s. Contact with a complex antigen such as a virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
will stimulate multiple immune responses
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
to the virus' different macromolecules as well as the individual epitopes of each macromolecule. For example, the tetanus
Tetanus
Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani...
toxin is a single protein macromolecular antigen but will stimulate many immune responses due to the tertiary structure of the protein yielding many different epitopes.
Medicinal uses for this idea include immunization
Immunization
Immunization, or immunisation, is the process by which an individual's immune system becomes fortified against an agent ....
to bacterial 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...
s. The toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
that creates the immune response will have an epitope on it that stimulates the response. Denaturing
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
the protein may 'disarm' its function but allow the immune system to have an immune response thus creating an immunity without harming the patient.
Cross-reactivity is also a commonly evaluated parameter for the validation of immune and protein binding based assay
Assay
An assay is a procedure in molecular biology for testing or measuring the activity of a drug or biochemical in an organism or organic sample. A quantitative assay may also measure the amount of a substance in a sample. Bioassays and immunoassays are among the many varieties of specialized...
s such as 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...
and RIA
RIA
RIA can stand for:* Russian Information Agency "RIA Novosti"* Royal Irish Academy* Rich Internet Application* Research into Ageing* Radioimmunoassay* National Rail code for Rhoose Cardiff International Airport railway station, Wales...
. In this case it is normally quantified by comparing the assays response to a range of similar analytes and expressed as a percentage. In practice, calibration curve
Calibration curve
In analytical chemistry, a calibration curve is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration...
s are produced using fixed concentration ranges for a selection of related compounds and the mid-points (IC50
IC50
The half maximal inhibitory concentration is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance is needed to inhibit a given biological process by half...
) of the calibration curves are calculated and compared. The figure then provides an estimate of the response of the assay to possible interfering compounds relative to the target analyte.
Examples
Hevein-like protein domains are a possible cause for allergen cross-reactivity between latexLatex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
and banana
Banana
Banana is the common name for herbaceous plants of the genus Musa and for the fruit they produce. Bananas come in a variety of sizes and colors when ripe, including yellow, purple, and red....
.