A 15-year old healthy boy with no major medical problem complaints that he breaks out with blocky areas of erythema that are pruritic over skin of his arm, leg and trunk every time within an hour of eating sea foods. The clinical features are suggestive of:
Type I hypersensitivity is also known as immediate or anaphylactic hypersensitivity. The reaction may involve skin (uicaria and eczema), eyes (conjunctivitis), nasopharynx (rhinorrhea, rhinitis), bronchopulmonary tissues (asthma) and gastrointestinal tract (gastroenteritis). The reaction may cause a range of symptoms from minor inconvenience to death. The reaction usually takes 15 - 30 minutes from the time of exposure to the antigen, although sometimes it may have a delayed onset (10 - 12 hours). Ref:Nandini Shetty (2006), Chapter 15, " Hypersensitivity", In the book, "Immunology: Introductory Textbook", 2nd Edition, New Delhi, Pages 126-128.
Localised immune-complex deposition
Cell mediated hypersensitivity
Localized anaphylaxis
Release of complement C3b