ELISA heat map of discovery set samples. We performed sequential ELISA as described in “Antibody array methods” on samples from 21 GVHD⁻ patients (left panel) and 21 GVHD⁺ patients (right panel) of the discovery set that were analyzed by microarray in Figure S1. Gray indicates that the sample was not assayed for that protein. Levels of PSA-ACT, IL-17, and IL-1β were not detectable and therefore do not appear in the figure. We measured tumor-necrosis-factor-receptor-1 (TNFR1) rather than TNF-α because of its close correlation to TNF-α and documented reproducibility of measurement in previously frozen samples.¹ P values compare GVHD⁺ and GVHD⁻ samples.