Abstract
The explanation of hypersensitivity reactions has long relied on the classification of Gell and Coombs, originally proposed in the 1960s. However, their concepts were predated by other authors by at least 50 years. A 21st century pediatric allergy clinic provides multiple examples of these basic concepts on a daily basis. We review classic and less classic examples of the original criteria, highlight where current disease pathophysiology does not always fit the original model, and provide updated language for common and uncommon immunologically driven hypersensitivity diseases.