Marie-Therese Heemels

Direct binding of peptide to empty MHC class I molecules on intact cells and in vitro

MHC class I molecules devoid of peptide are expressed on the cell surface of the mouse mutant lymphoma cell line RMA-S upon culture at reduced temperature. Empty class I molecules are thermolabile at the cell surface and in detergent lysates, but can be stabilized by the addition of presentable peptide; peptide binding appears to be a rapid process. Furthermore, class I molecules on the surface of RMA-S (H-2b haplotype) cells cultured at 26 degrees C can efficiently and specifically bind iodinated peptide presented by H-2Kb. Binding of iodinated peptide is also observed at a lower level for nonmutant cells (RMA) cultured at 26 degrees C. These experiments underscore the role for peptide in maintenance of the structure of class I molecules and, more importantly, provide two assay systems to study the interactions of peptides with MHC class I molecules independent of the availability of T cells that recognize a particular peptide-MHC class I complex.

Medicine Nobel goes to pioneer of protein guidance mechanisms.

LondonThe 1999 Nobel Prize for Physiology or Medicine

Alzheimer's disease: Plaque removers and shakers

Progress in understanding Alzheimers disease comes with a report that Alzheimers like pathology in mice can be halted by antibodies that recognize the amyloid-b peptide, found in the brain plaques characteristic of the human disease. The antibodies bind to the plaques and trigger their removal.

Immunology. Fetal fascination.

A mother readily rejects organ transplants from her offspring. Owing to the contribution of paternal genes, her childs tissues express different antigens to her own — and thats what gets her immune system going. Yet she carries these genetically disparate fetuses to term. What protects a fetus from attack by its mothers immune system? Reporting in Science (281, 1191-1193; 1998), Andrew Mellor and colleagues propose that, in mice, rapid consumption of the amino acid tryptophan at the maternal-fetal interface paralyses the mothers aggressive T cells.