Fig 2: High TNF production by CD155 expressing APCs. Flow cytometry analysis of psoriatic disease patients PBMCs stimulated for 4 hours with LPS (100 ng/ml) in the presence of Brefeldin A (1:1000). (A) Proportion of TNF producing cells within CD155-positive and CD155-negative APC subsets of psoriasis patients (n = 13, open symbol) and psoriatic arthritis patients (n = 15, filled symbol): CD14+CD16- classical monocyte (cM), CD1c+ myeloid dendritic cell (mDC), and CD123+ plasmacytoid dendritic cell (pDC) (detailed gating strategy shown in Supplementary Fig. S1B). (B–D) Representative flow plots of TNF production by CD1c+ mDC: CD155-positive TNF FMO control (B), CD155-negative CD1c+ mDC (C), and CD155-positive CD1c+ mDC (D). *Significant P-value MWU. NA: not applicable.

Fig 3: Plasma Cytokines and Immunophenotyping, Related to Figure 5(A-M) Quantitation of plasma cytokine levels from acute (n = 24) and unexposed (n = 15) donors: (A) CXCL10, (B) IL-8, and (C) IL-6. (D) IL-1b, (E) TNFa, (F) IFNl1, (G) IL12p70, (H) IFNa2, (I) IFNl2, (J) GM-CSF, (K) IFNb, (L) IL-10, (M) IFNg. (N) Correlation of CD3-CD19- PBMCs and peak disease severity. Statistics are reported for convalescent and acute samples.(O-P) Correlation of (O) activated CD4 T cells with combined AIM+ CD4 T cells and (P) activated CD8 T cells with combined AIM+ CD8 T cells across all donors. Statistics are reported for unexposed, convalescent and acute samples.(Q) Correlation of (CD38hiCD20-CD19+) plasmablasts with RBD IgG titers. Statistics are reported for unexposed and acute samples.(R) Gating strategies for plasmablasts and T cell subtypes. The black dotted line indicates LOD; the green dotted line demarcates marginal responses as determined by unexposed donor responses. Pink dots denote samples where two or more peptide pools were not run due to cell numbers. Acute (Ac) = Red, Convalescent = black, Unexposed (Unexp) = gray.***p < 0.001, ****p < 0.0001, NS = not significant.

Fig 4: The route of antigen exposure does not greatly impact the direct ex vivo functionality of antigen-specific cellsPBMCs were stimulated with C19 (YLQPRTFLL) or FLU (GILGFVFTL) peptide for 4 h in the presence of brefeldin A and analyzed by flow cytometry.(A) Representative FACS plots (top row) and quantification of data (bottom row) are shown. Numbers indicate percentages within the quadrant. Cells are gated for live CD3+CD8+ cells. BrefA control, cells stimulated with brefeldin A only (n = 16).(B) Donut graphs showing polyfunctional analysis of C19- and FLU-specific CD8+ T cells. Relative distribution of single or multiple cytokine-producing cells is shown for IL-2, IFN?, and TNF (n = 16).(C and D) PBMCs were stimulated with a peptide pool of immunodominant epitopes of the spike protein of SARS-CoV-2 or of influenza HA for 4 h in the presence of brefeldin A and analyzed by flow cytometry.(C) Percentage of cells expressing the indicated activation-induced markers (AIMs) (n = 18).(D) (Top row) Representative FACS plots and (bottom row) quantification of cytokine expression (n = 24). Indicated are means ± SEM.Statistical significances at *p < 0.05 and **p < 0.01 using one-way ANOVA followed by Bonferroni post-testing (A, C, and D).See also Figure S2.