1,1,1,3,3,3-Hexafluoroisopropanol (HFIP) is a polar, strongly hydrogen bond-donating solvent that has found numerous uses in organic synthesis due to its ability to stabilize ionic species, transfer protons, and engage in a range of other intermolecular interactions. The use of this solvent has exponentially increased in the past decade and has become a solvent of choice in some areas, such as C–H functionalization chemistry. In this review, following a brief history of HFIP in organic synthesis and an overview of its physical properties, literature examples of organic reactions using HFIP as a solvent or an additive are presented, emphasizing the effect of solvent of each reaction.

ERRATUM TO: USE OF A MAIT ACTIVATING LIGAND, 5-OP-RU, AS A MUCOSAL ADJUVANT IN A MURINE MODEL OF VIBRIO CHOLERAE O1 VACCINATION DOI: 10.20411/pai.v7i1.525 Reason: The authors sincerely regret the inadvertent omission of Jackson G. Cacioppo as coauthor of this work. He has no additional conflicts of interest.  Corrected version: Owen Jensen1,2, Shubhanshi Trivedi1, Jackson G. Cacioppo3, Kelin Li3, Jeffrey Aubé3, J. Scott Hale2, Edward T. Ryan4,5,6, Daniel T. Leung1, 2*

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Mucosal-associated invariant T (MAIT) cells are promising innate-like lymphocytes with potential for use in anti-tumor immunotherapy. Existing MAIT cell expansion protocols are associated with potentially decremental phenotypic changes, including increased frequency of CD4+ MAIT cells and higher inhibitory receptor expression. In this study, we compared the effect on human MAIT cells of a serum replacement, Physiologix XF SR (Phx), with traditional serum fetal bovine serum (FBS) for supplementing RPMI-1640 media. Using flow cytometry, we found that Phx supported a significantly higher proliferative capacity for MAIT cells and resulted in a lower frequency of CD4+ MAIT cells. We saw that culturing MAIT cells in Phx allowed for better survival of MAIT cells and lower frequency of PD-1+ MAIT cells compared to FBS-supplemented media. Functionally, we saw that Phx supplementation was associated with a higher frequency of IFN-γ+ MAIT cells after stimulation with E. coli compared to FBS-supplemented RPMI. In conclusion, we show that MAIT cells cultured in Phx have higher proliferative capacity, lower expression of inhibitory receptors, and have higher capacity to produce IFN-γ after E. coli stimulation, compared to FBS-supplemented RPMI. This work shows that expanding MAIT cells with Phx compared to FBS-supplemented RPMI result in a more functionally desirable MAIT cell for future anti-tumor immunotherapy.

Mucosal-associated invariant T (MAIT) cells are promising innate-like lymphocytes with potential for use in anti-tumor immunotherapy. Existing MAIT cell expansion protocols are associated with potentially decremental phenotypic changes, including increased frequency of CD4+ MAIT cells and higher inhibitory receptor expression. In this study, we compared the effect on expansion of human MAIT cells of a serum replacement, Physiologix XF SR (Phx), with traditional serum FBS for supplementing RPMI 1640 media. Using flow cytometry, we found that Phx supported a significantly higher proliferative capacity for MAIT cells and resulted in a lower frequency of CD4+ MAIT cells, which have been associated with reduced Th1 effector and cytolytic functions. We saw that culturing MAIT cells in Phx led to better survival of MAIT cells and lower frequency of PD-1+ MAIT cells than FBS-supplemented media. Functionally, we saw that Phx supplementation was associated with a higher frequency of IFN-γ+ MAIT cells after stimulation with Escherichia coli than FBS-supplemented RPMI. In conclusion, we show that MAIT cells cultured in Phx have higher proliferative capacity, lower expression of inhibitory receptors, and higher capacity to produce IFN-γ after E. coli stimulation than FBS-supplemented RPMI. This work shows that expanding MAIT cells with Phx compared with FBS-supplemented RPMI results in a more functionally desirable MAIT cell for future anti-tumor immunotherapy.

4′-Phosphopantetheinyl transferase (PptT) is an essential enzyme for Mycobacterium tuberculosis (Mtb) survival and virulence and therefore an attractive target for a tuberculosis therapeutic. In this work, two modeling-informed approaches toward the isosteric replacement of the amidinourea moiety present in the previously reported PptT inhibitor AU 8918 are reported. Although a designed 3,5-diamino imidazole unexpectedly adopted an undesired tautomeric form and was inactive, replacement of the amidinourea moiety afforded a series of active PptT inhibitors containing 2,6-diaminopyridine scaffolds.