Fig. 1: SLB2s balance antigen sensitivity and specificity.

a–d Calcium response curves for J8-GECI cells on the indicated SLBs presenting pMHC^null ± pMHC^9V. A cartoon indicating the SLB compositions is shown (top panel), along with the fraction of cells exhibiting a Ca²⁺ signal (middle panel) and the time taken for 50% of the cells to signal (bottom panel). Each datapoint corresponds to a separate SLB. Data were fitted with a four-point dose-response curve, constrained to a minimum using responses to pMHC^null. a “First generation” SLB (‘SLB1’; black); n = 44 SLBs with ≥116 cells analyzed per SLB. b SLB1 + CD58 (cyan); n = 28 SLBs with ≥127 cells analyzed per SLB. c SLB1 + glycocalyx (magenta); n = 23 SLBs with ≥140 cells analyzed per SLB. d “Second generation” SLB (‘SLB2’; blue); n = 42 SLBs with ≥109 cells analyzed per SLB. e, f Spreading, synapse formation, and calcium release for J8-GECI cells interacting with non-adhesive (ΔICAM-1ΔCD58) to highly adhesive (ΔCD43ΔCD45) SLBs. All the SLBs presented pMHC^null, except for the right-most SLB2, which presented pMHC^null plus pMHC^9V at ~100 molecules/μm². J8-GECI cells were tracked for calcium signals for 10 min and immediately imaged afterward to allow IRM-based contact area measurement and synapse formation frequency. e Images of cells spreading (dark areas in IRM image) and forming synapses. Colored boxes denote the same SLB composition shown in (a–d). Images are representative of J8-GECI cells on n = 4 independent SLBs for each SLB composition. f Left plot: fraction of cells that exhibit a calcium signal. Shown is the mean (±S.D.) of n = 4 independent SLBs with ≥158 cells analyzed per SLB. ΔCD43ΔCD45, ΔCD58, and SLB2s presenting pMHC^null correspond to the zero density values in (b), (c), and (d), respectively. f Middle plot (log scale): quantification of cell spreading; n = 115 (ΔICAM-1ΔCD58), 133 (ΔCD58), 174 (ΔICAM-1), 154 (SLB2 pMHC^9V−), 132 (ΔCD43), 108 (ΔCD45), 118 (ΔCD43ΔCD45), and 122 SLB2 (SLB2 pMHC^9V+) cells pooled from four independent SLBs for each SLB composition. The red line indicates median. f Right plot: quantification of synapse formation. Shown is the mean (±S.D.) fraction of cells forming synapses from n = 4 independent SLBs with ≥17 cells analyzed per SLB. In f, means were compared to an SLB2 presenting pMHC^null via one-way ANOVA with Tukey correction. Comparison between the ΔCD43ΔCD45 SLB and SLB2 (with pMHC^9V) was also included. Only statistics for comparisons of interest are shown. Source data are provided in the Source data file.