A subpopulation of T cells recognizes antigens derived from lipids, rather than from proteins, and these lipid antigens are presented by members of the CD1 family of cell surface proteins. However, one CD1 family member, CD1e, does not seem to present lipids directly. De la Salle et al. observed that a lipid antigen that depends on processing to stimulate T cells via another member of the CD1 family (CD1b) could not do so in the absence of CD1e. CD1e was required to assist in modifying a lipid precursor within the lysosome, which allowed intracellular association with CD1b and subsequent presentation to T cells. Thus, the role of this remaining CD1 family member appears to involve processing rather than direct presentation of antigenic lipids to T cells.
H. de la Salle, S. Mariotti, C. Angenieux, M. Gilleron, L. F. Garcia-Alles, D. Malm, T. Berg, S. Paoletti, B. Maître, L. Mourey, J. Salamero, J. P. Cazenave, D. Hanau, L. Mori, G. Puzo, G. De Libero, Assistance of microbial glycolipid antigen processing by CD1e. Science 310, 1321-1324 (2005). [Abstract] [Full Text]