CD1 molecules are a family of cell surface-associated glycoproteins now rec
ognized as having a role in antigen presentation. These glycoproteins are d
istinct from yet have some similarities to classical major histocompatibili
ty complex class I and class H molecules. The role of these molecules has b
een studied in detail over recent years, with an explosion of interest foll
owing the demonstration that they can present nonprotein antigens to certai
n subpopulations of T cells. The purpose of this paper is to provide an ove
rview of current knowledge of the function of the CD1 family with specific
emphasis on the potential role in the pathogenesis of certain diseases. Alt
hough much of the current research in this field has inevitably concentrate
d on mice and humans, this work also has potential significance for veterin
ary species.