An issue that sets immunomic microarray data apart is the availability of vector-valued response profiles (in the case of peptide-MHC microarrays). The statistical challenge here is reminiscent of the data analysis problem in the engineering field of remote sensing [105] , where different materials have characteristic vector responses, called spectral signatures. In the case of immunomic data, the analogous notion to the spectral signature is the cytokine profile associated with a given epitope and T cell population; see Figure 4 for an illustration. One simple technique to address the data analysis problem for multicolor immunomic data is to combine the responses into one long feature vector, by juxtaposing the individual cytokine response profiles for each epitope, with the caveat that there may be systematic correlation among the features in the resulting feature vector.