What is Cytotoxicity?
Cytotoxicity refers to the internal harm to tissues that results from chronic exposure to toxins. Examples of toxic substances are poison ivy, anacardic, or some forms of poison, e.g. from the poison ivy spider or a brown recluse. Allergic reactions, such as anaphylactic shock, can also produce cytotoxic reactions. Cytotoxicity can be assessed by the cytotoxicity assay.
Types of Cytotoxicty
Cytotoxicity can be either local or systemic. Local cytotoxicity is experienced when the toxins enter the blood stream and affect cells in the immediate vicinity. This is often the result of a low-grade ingested toxin. Systemic cytotoxicity, however, occurs when toxic substances are injected, ingested, or otherwise enter the body. The most common method of systemic cytotoxicity through insect bites, especially poison ivy.
Cytotoxicity Related Diseases?
Some of the most common genetic diseases which can produce cytotoxic agents include Parkinson's disease and Huntington's choreitis, both of which share a similarity in the cytotoxic mechanism.
Cytotoxic agents can also be produced by the metabolic action of some medications, including some cancer drugs. Several environmental agents are now known to cause toxicity, including environmental chemicals and pesticides. In addition, radiation has been shown to cause certain forms of cancer.
Cytotoxicity can affect any cell in the body, but it typically affects cells that are rapidly dividing and secrete plasma membranes. Some examples of rapidly dividing cells, which can generate toxic agents are the skin cells and the red blood cells.
Cytotoxic agents may also be generated by lymphocytes and white blood cells in response to an injury, infection, or illness. Even normal cells can develop cytotoxicity over time as a result of certain conditions, such as those that involve high cellular and oxidative stress. The main cytotoxicity factor is oxygen cytotoxicity, which results from oxygen deprivation.
Cytotoxic Activities
Cytotoxic activity can be revealed by one of two methods: by changes in DNA base pairing or by changes in the concentration of the oxygen molecules.
Cytotoxicity can be caused by alterations in DNA base pairing; for instance, cytotoxicity caused by an increase in the base composition of an individual DNA sequence (oxygen-based) or an increase in its acceptor base (nitric oxide). The increased base composition of an individual DNA sequence, however, does not always yield an increase in its acceptor or vice versa. If this is the case, then there would be no cytotoxicity.
What does happen in Cell?
On the other hand, if two daughter cells divide into two daughter cells, then this division will trigger a chain reaction of events that can damage or destroy the cells involved. One of the important concepts of genetics is that of cell division. The DNA of each cell has a set of instructions on how to divide into a pair of daughter cells. These instructions are passed down from parent to daughter through the cell cycle.
Mechanism of Cytotoxicity
- During cell division, a phosphate-based Kinase (K), a protein that helps regulate the division of cells, releases a cytosine, or messenger ribonucleic acid (mRNA).
- There are two distinct forms of messenger ribonucleic acid, a single-stranded form that is used by all cells and a double-strand form that is used by a few select cells, like lymphocytes.
- Upon receipt of the mRNA from one of the parental cells, the K protein binds with the mRNA. In the absence of the K protein, or upon stimulation by an outside chemical such as oxygen or other light, the mRNA will separate into a non-mutable or mutable form. Either way, upon its release into the culture media, the two strands of mRNA become identical.
- Cytotoxicity can occur when either the mRNA and DNA do not differentiate during cell division resulting in the wrongful separation of the cells. This results in the formation of a cyst.
- Cysts can then be passed to the next generation, called a blastocyst. If the culture of the clump of cells containing the new-formed cysts is not terminated promptly, the cysts can grow to numbers that can block an artery or even form a tumor.
- Cytotoxicity may be caused by some naturally occurring chemicals, but there are also numerous reports of exposure to certain drugs and pesticides causing significant damage to DNA. If there are more than two daughter cells produced in the blastocyst, this is referred to as hypercellularization.
