Multimodal identification of rare potent effector CD8 T cells in solid tumors.

Antitumor immunity is driven by CD8 T cells, yet we lack signatures for the exceptional effectors in tumors, amongst the vast majority of CD8 T cells undergoing exhaustion. By leveraging the measurement of a canonical T cell activation protein (CD69) together with its RNA (Cd69), we found a larger classifier for TCR stimulation-driven effector states in vitro and in vivo. This revealed exceptional 'star' effectors-highly functional cells distinguished amidst progenitor and terminally exhausted cells. Although rare in growing mouse and human tumors, they are prominent in mice during T cell-mediated tumor clearance, where they engage with tumor antigen and are superior in tumor cell killing. Employing multimodal CITE-Seq allowed de novo identification of similar rare effectors amidst T cell populations in human cancer. The identification of rare and exceptional immune states provides rational avenues for enhancement of antitumor immunity.

Quantitative Effects of O-Linked Glycans on Protein Folding.

Protein O-glycosylation is a diverse, common, and important post-translational modification of both proteins inside the cell and those that are secreted or membrane-bound. Much work has shown that O-glycosylation can alter the structure, function, and physical properties of the proteins to which it is attached. One gap remaining in our understanding of O-glycoproteins is how O-glycans might affect the folding of proteins. Here, we took advantage of synthetic, homogeneous O-glycopeptides to show that certain glycosylation patterns have an intrinsic effect, independent of any cellular folding machinery, on the folding pathway of a model O-glycoprotein, a carbohydrate binding module (CBM) derived from the Trichoderma reesei cellulase TrCel7A. The strongest effect, a 6-fold increase in overall folding rate, was observed when a single O-mannose was the glycan, and the glycosylation site was near the N-terminus of the peptide sequence. We were also able to show that glycosylation patterns affected the kinetics of each step in unique ways, which may help to explain the observations made here. This work is a first step toward quantitative understanding of how O-glycosylation might control, through intrinsic means, the folding of O-glycoproteins. Such an understanding is expected to facilitate future investigations into the effects of glycosylation on more biological processes related to protein folding.