ABSTRACT
What is a restriction element and how is it recognized? One of the key questions in studies of MHC polymorphism is discussed by van Schravendijk, Coligan, and Biddison in their comparison of class I structure and function. Sequence analysis of HLA variants pinpoints particular “variable” sequences which appear to form recognition epitopes for T-cells, but paradoxically not for B-cells. Does this difference indicate something important in receptor structure and specificity? In regulatory mechanisms?
