Identification of Nonpeptide Antigens for gamma delta T Cells
EMSL Project ID
2074
Abstract
In this proposal, we plan to characterize nonpeptide antigens for gamma delta T cells. Human gd T cells expressing Vg2Vd2 T cell receptors recognize nonpeptide antigens. We identified one antigen as isopentenyl pyrophosphate but it was clear that a number of antigens existed in bacteria. To determine the structure of the additional antigens from bacteria, we purified the major bioactive antigen from Mycobacterium smegmatis by carbon filtration, ultrafiltration, anion exchange chromatography, and ion-pairing reverse phase chromatography. By tandem mass spectrometry, the antigen has a molecular weight of 262 Daltons and contains a pyrophosphate moiety. The same antigen was also isolated from Mycobacterium fortuitum, and appears to be present in Yersinia enterocolitica, a Gram-negative rod, and Staphylococcus aureus, a Gram-positive cocci. The antigen is likely to be an undescribed intermediate in the deoxyxylulose synthetic pathway for isopentenyl pyrophosphate that is present in eubacteria, apicomplexan protozoa, and plants. By recognizing a common biosynthetic intermediate, gd T cells are using pattern recognition to determine when to mount an adaptive immune response. For our studies at the EMSL, we propose to characterize the 262 Dalton compound and other compounds by FTICR mass spectrometry to measure exact masses. Given the small size of the compounds and the limited types of elements, chemical compositions can be determined. Earlier studies at the EMSL successfully determined the chemical composition of a number of phosphorylated compounds and lead to their identification. The identity of compounds will be verified by fragmentation mass spectrometry. Instruments to be used in this proposed study: 7 tesla FTICR
Project Details
Project type
Exploratory Research
Start Date
2000-11-03
End Date
2001-12-31
Status
Closed
Released Data Link
Team
Principal Investigator