SummaryGroup 2 innate lymphoid cells (ILC2s) release interleukin-13 (IL-13) during protective immunity to helminth infection and detrimentally during allergy and asthma. Using two mouse models to deplete ILC2s in vivo, we demonstrate that T helper 2 (Th2) cell responses are impaired in the absence of ILC2s. We show that MHCII-expressing ILC2s interact with antigen-specific T cells to instigate a dialog in which IL-2 production from T cells promotes ILC2 proliferation and IL-13 production. Deletion of MHCII renders IL-13-expressing ILC2s incapable of efficiently inducing Nippostrongylus brasiliensis expulsion. Thus, during transition to adaptive T cell-mediated immunity, the ILC2 and T cell crosstalk contributes to their mutual maintenance, expansion and cytokine production. This interaction appears to augment dendritic-cell-induced T cell activation and identifies a previously unappreciated pathway in the regulation of type-2 immunity.

A myosin for RNA Pol II T ranscription gets a boost from myosin VI, according to fi ndings from Sarah Vreugde (DIBIT Scientifi c Institute, Milano, Italy) and colleagues. The motor might drag genes into transcription neighborhoods. While trying to understand the function of myosin VI, Vreugde noticed that its localization pattern looked much like that of RNA polymer-ase II. The authors then showed an association between the motor and polymerase that depends on ongoing transcription. By cross-linking myosin VI to chromatin, the group identifi ed several genes at which the motor is found. The mRNA levels of these genes decreased when myosin VI levels were reduced. Vreugde next hopes to inhibit just the nuclear pool of myosin VI and then do genome-wide analyses to identify more affected genes. Assuming its infl uence is widespread, the motor might spool the DNA past aggregates of RNA polymerases or recruit stretches of DNA to transcription factories. "DNA recruitment to transcription factories would be heavy work," says Vreugde. "But myosin is well-suited to accomplish that." Whether its unusual preference to move toward actin minus ends helps myosin VI at all is unclear, as the polarity of the nuclear actin network is not known and probably dynamic. The only other known nuclear myosin, myosin I, is plus-end directed but still enhances transcription by all the RNA polymerases.