Still innate lymphoid cells have been shown to express MHC class II molecules, indicating that they can present antigens and may also contribute to initiation of T cell responses. In addition, ILC2s have been shown to release IL-5 and IL-13, representing an early source of these cytokines in type-2 immunity. In accordance, ILC2s have been attributed important protective functions against parasitic worm infections. GDC-0879 Recently a study demonstrated the presence of natural helper cells in aortic samples from mice and isolated aortic natural helper cells were found to produce IL-5 in response to IL-33 treatment. B2 cells respond to T cell-dependent antigens, whereas B1 cells seem to be involved mainly in T cell-independent immune responses. B1 cells are the major B cell population in the LY2157299 peritoneal and pleural cavities in mice and the main producers of natural antibodies. These antibodies are specific for self-antigens such as the phosphocholine headgroup of oxidized phospholipids expressed on oxidized low density lipoprotein and apoptotic cells. B1 cells expressing CD5 are called B1a cells, whereas a minor subset of B cells that do not express CD5 but closely resemble these CD5+ B1a cells are known as B1b cells. Previous experimental findings have shown that conventional B2 cells contribute to atherosclerosis development, whereas peritoneal B1a cells are athero-protective by producing natural IgM. Several lines of evidence indicate that adaptive immune responses contribute to the development of atherosclerosis by promoting inflammation and plaque growth. However, immunization of hypercholesterolemic animals with native or oxidized LDL unexpectedly resulted in a significant reduction of atherosclerosis development, suggesting that both atherogenic and protective immune responses exist. Th1 effector cells are believed to drive the disease, since deletion of Th1 promoting cytokines and transcription factors have been found to reduce the development of atherosclerosis, whereas studies on T regulatory cells have pointed to a protective role. Studies of the role of Th2 immune responses in atherosclerosis have given an inconsistent picture. IL-4 has been found to exert both pro- and anti-atherogenic effects depending on the experimental conditions, whereas IL-5 has been attributed athero-protective properties by inducing natural IgM antibodies specific to epitopes of oxidized LDL. In addition, IL-33 has been suggested to play a protective role in the development of atherosclerosis via the induction of IL-5 and ox-LDL antibodies. In this study we asked, whether administration of IL-25 to apoE deficient mice has any influence on atherosclerosis development.