Figure 4.

Long-term storage of cryopreserved MHC multimers. Results obtained in three independent tests performed are shown. (A) HLA-A2 EBV_GLC MHC multimers with different fluorescent labels (APC, PE, QD605, QD705) were cryopreserved with 0.5% BSA and 5, 10, or 15% glycerol for 6 months. The staining index of the MHC multimer population is depicted compared to a not stored control prepared each time 1 day prior to staining (performed by Center 2, one donor, n = 1). (B) Long-term stability of three different HLA-A2 multimers (PE-EBV_YVL, APC-FLU_GIL, QD705 CMV_NLV) was assessed after 1 week up to 13 months storage for two different donors (indicated by gray or black symbols). The staining index of the MHC multimer population is depicted relative to a not stored control of the same batch of monomers tested directly after preparation, before cryopreservation (left plot, 1 week-6 months) or compared to a freshly-prepared batch of multimers for the additional time points, 9 and 12 months (right plot), (performed by Center 1, n = 1). (C) SI after storage at −20°C vs. −80°C, for MHC multimers refolded with virus-derived epitopes: A2 CMV_NLV, A2 EBV_FLY, B7 CMV_TPR labeled with PE or QD605, used for staining PBMC (black symbols) or MHC multimers with cancer-associated epitopes A2 MART_ELA (modified) and A2 MART_EAA (wt) used for staining TILs (gray symbols) (performed by Center 3, n = 1).