Delayed hypersensitivity refers to a condition of the body, wherein a reaction to certain stimuli takes time to occur. In most cases, if the body reacts to something, it happens almost immediately. However, in people who suffer from delayed hypersensitivity, the immune system takes anywhere between twenty four and seventy two hours to react to the stimuli or microbe. Most often, the reactions that take place do so with violent force. Contrary to the reactions of antibodies that cause immediate hypersensitivity, delayed hypersensitivity is caused by reactions of the lymphocytes. Delayed cutaneous hypersensitivity refers to the reaction of the body with respect to tumor cells.
A delayed hypersensitivity test is a test that is conducted in order to find out the reaction of lymphocytes to a particular substance. There are three primary reasons for which delayed hypersensitivity testing is carried out. The most important of the three is to test for specific diseases. For example, the antigen of the tuberculosis disease is injected into the body of the person. Though there are no live or dead organisms of the illness present, it can still cause a reaction. Similarly, it is used to check the sensitivity of the skin to certain irritants.
Delayed hypersensitivity tests are also carried out to judge the reaction time of the lymphocytes in certain illnesses, such as cancer or AIDS, where the immune system of the body undergoes a great deal of damage. The delayed cutaneous hypersensitivity test is carried out mainly in women who are suspected of having cancer of the breast. The objective of the delayed cutaneous hypersensitivity test is also to check the level of reaction to certain antigens in people who have been tested positive for the Human Immunodeficiency Virus. Once the allergen has been located, it is advisable for people with delayed hypersensitivity to stay away from the allergen itself.
The most commonly used method of hypersensitivity testing is through injecting a person with an antigen. In the event that there is a reaction that occurs, it most commonly manifests in the hardening and redness of the area where the hypersensitivity test injection has been administered. Skin hypersensitivity testing can also be done by placing adhesive pads that contain the antigen of the suspected irritant in contact with the skin. In delayed cutaneous hypersensitivity testing, the test is carried out in the primary area of the malignancy and the reaction to the antigen is recorded thereof.