Fig 1: Characterization of innate lymphoid cells in the blood of COVID-19+ individuals out to 4 weeks of SARS-CoV-2 infection. Healthy controls and COVID-19+ samples were collected as before (Figure 1); hospitalized patient samples were not included as most of these individuals experience lymphopenia, and ILC were not readily detected by flow. (A) Total innate lymphoid cells (ILC) were identified as lineage negative (Lin- (CD3-, CD19-, CD11c-, CD11b-, CD15-, TCR αβ-, TCR γδ-, Ter-119, and Ly-76)) following by inclusive gating for CD45 and CD127. (B) Group 2 innate lymphoid cells (ILC2) were CD45+ Lin- and CD127+, with additional gating on CD25+ and CRTH2+ cells. (C) Group 3 innate lymphoid cells (ILC3) were gated as CD45+ Lin- CD127+, followed by gating for CD25, NKp46+, and ICOS-positive cells, whereas (D) natural killer cells (NK) were CD25+ NKp46+, and ICOS-. (A–D) represents each population as a percentage of the viable CD45+ cells. (E) Interferon (IFN) γ production by enriched ILC cultured with the ILC prosurvival cytokines, IL-2 and IL-7, and the ILC activating cytokines (IL-23, IL-33) was assessed using a protein array. Statistical differences were determined in the same way as before using a two-way ANOVA with post-testing to make between COVID-19+ groups (d0 vs. d7, d7 vs. d28, d0 vs. d28 by post-test) comparisons. As before, * indicates a p = 0.05 or less, ** less than p = 0.01, and *** indicates p < 0.001. A Student’s t-test was used to compare the healthy control group to each COVID-19+ group; # p < 0.05, ## p < 0.01, #### p < 0.0001 by t-test. For healthy controls, n = 15, and for COVID-19+ individuals, n = 14.