The term "Delayed Hypersensitivity", used in immunology, describes an antigen-specific immune response that occurs several hours or days after initial exposure to an antigen. Its phonetic transcription is /dɪˈleɪd hʌɪpərsɛnsətɪvɪti/. The spelling of this word can be explained through the International Phonetic Alphabet (IPA), where each letter represents a specific sound or phoneme. In this transcription, the symbols /d/, /ɪ/, /s/, /ɛ/, /t/, /v/ represent English sounds that make up the word's pronunciation.
Delayed hypersensitivity refers to an exaggerated immune response that occurs after exposure to an antigen, resulting in a delayed or prolonged inflammatory reaction. This type of hypersensitivity is characterized by a T cell-mediated immune response, rather than an immediate antibody response seen in other types of hypersensitivity reactions.
Delayed hypersensitivity is typically observed in response to certain antigens such as pathogens, allergens, or environmental substances like chemicals or metals. Upon exposure, the immune system recognizes these antigens as foreign and activates T cells called helper T cells or TH cells. These TH cells release chemical messengers called cytokines, which recruit other immune cells to the site of antigen exposure.
This immune response is often delayed, taking anywhere from 24 to 72 hours to develop after initial exposure. It is this delayed onset that distinguishes delayed hypersensitivity from other hypersensitivity reactions, which typically occur within minutes to hours after exposure.
The prolonged activation of immune cells leads to an inflammatory response characterized by redness, swelling, and tissue damage at the site of antigen exposure. This inflammatory reaction can be seen in conditions such as contact dermatitis, tuberculosis, allergic reactions to certain medications, or autoimmune diseases like rheumatoid arthritis.
In summary, delayed hypersensitivity refers to an immune response that occurs after exposure to an antigen, resulting in a delayed or prolonged inflammatory reaction mediated by T cells. It is characterized by a delayed onset and is often associated with conditions involving inflammation and tissue damage at the site of antigen exposure.
The term "Delayed Hypersensitivity" refers to a type of immune response that occurs several hours or even days after exposure to an antigen. The etymology of the word can be broken down as follows:
1. Delayed: The word "delayed" comes from the Old French word "delaiier", which means "to put off" or "to postpone". It can be traced back to the Latin word "dilatum", which has the same meaning.
2. Hypersensitivity: The word "hypersensitivity" is a combination of two terms. "Hyper-" is a prefix derived from Greek, meaning "over" or "excessive". "Sensitivity" comes from the Latin word "sensus", which means "perception" or "feeling".