A recent study describes direct binding between a gamma delta T-cell recept
or and its ligand, T22, a non-classical class I major histocompatibility co
mplex (MHC) molecule. A companion study, solving the crystal structure of T
22, highlights the differences between this interaction and those of classi
cal MHC molecules and alpha beta T cells. (C) 2000 Elsevier Science Ltd. Al
l rights reserved.