NOD2 and Blau syndrome: This view of the Blau abnormality also applies to a recent study in which it was shown that macrophages derived from induced pluripotential stem cells (iPS cells) bearing Blau NOD2 mutations exhibited decreased cytokine responses when exposed to MDP but increased cytokine responses when cultured in the presence of IFN-γ; in addition, cells from one patient with Blau syndrome also exhibited heightened cytokine responses when cultured with IFN-γ (24).