- transcription factor interferon regulatory factor 4 (IRF4) = crucial transcription factor for different immune cells, incl pro-inflammatory Th17 and anti-inflammatory Treg cells - IRF4 is essential for the cell differentiation and fate determination - however molecular mechanisms of IRF4-mediated gene expression in fully differentiated Th17/Treg cells are still not fully understood - integration of data derived from affinity-purification and full mass spectrometry-based proteome analysis with chromatin immune precipitation sequencing (ChIP-Seq) - characterization of proteins generally involved in the T cell development as well as subtype-specific differentiation and identification of novel, yet uncharted IRF4 interactors