Short answers, pulled from the story.
Clemens von Pirquet coined the word allergy in 1906 after observing rapid severe reactions to second injections of horse serum or smallpox vaccine. He derived the term from Ancient Greek words allos meaning other and ergon meaning work.
The body produces immunoglobulin E antibodies that bind to specific receptors on immune cells like mast cells or basophils. When the allergen appears again it cross-links with these IgE molecules causing degranulation which releases histamine and other mediators into surrounding tissue.
Identical twins share the same allergic diseases about 70% of the time while non-identical twins show this trait only 40% of the time. Heredity remains the most significant host factor influencing allergy susceptibility across generations.
The RAST methodology was invented and marketed in 1974 by Pharmacia Diagnostics AB in Uppsala Sweden. In 1989 this company replaced it with a superior test named ImmunoCAP Specific IgE blood test using fluorescence-labeled technology.
Approximately 25% of the population develops a strong immune response to urushiol found in poison ivy plants. This reaction can cause skin contact issues resulting in dry crusted lesions lasting 48 to 96 hours.