Intraepithelial lymphocytes (IELs) expressing the γδ TCR (γδ IELs) provide continuous surveillance of the intestinal epithelium. However, the mechanisms regulating the basal motility of these cells within the epithelial compartment have not been well defined. We investigated whether IL-15 contributes to γδ IEL localization and migratory behavior in addition to its role in IEL differentiation and survival. Using advanced live cell imaging techniques in mice, we find that compartmentalized overexpression of IL-15 in the lamina propria shifts the distribution of γδ T cells from the epithelial compartment to the lamina propria. This mislocalization could be rescued by epithelial IL-15 overexpression, indicating that epithelial IL-15 is essential for γδ IEL migration into the epithelium. Furthermore, in vitro analyses demonstrated that exogenous IL-15 stimulates γδ IEL migration into cultured epithelial monolayers, and inhibition of IL-2Rβ significantly attenuates the basal motility of these cells. Intravital microscopy showed that impaired IL-2Rβ signaling induced γδ IEL idling within the lateral intercellular space, which resulted in increased early pathogen invasion. Similarly, the redistribution of γδ T cells to the lamina propria due to local IL-15 overproduction also enhanced bacterial translocation. These findings thus reveal a novel role for IL-15 in mediating γδ T cell localization within the intestinal mucosa and regulating γδ IEL motility and patrolling behavior as a critical component of host defense.

All humans and many animals can represent approximate quantities of perceptual objects nonlinguistically by using the Approximate Number System (Dehaene, 1997/2011). Early in life, children in numerate societies also learn to describe this system using number words. How do linguistic representations of number become related to nonlinguistic representations of number? We hypothesize that the analogical process of structure mapping (Gentner, 1983) helps children to form mappings between the linguistic and nonlinguistic number systems on the basis of structural similarities between the two systems. To test this, we tested and analyzed 47 four-and-ve year olds' performance on estimation and analogy tasks. We found that analogical reasoning ability uniquely predicted several components of estimation performance, even when controlling for other domain-general cognitive skills. This provides strong evidence that analogical processes are uniquely related to the development of early estimation.

All humans and many animals can represent approximate quantities of perceptual objects nonlinguistically by using the Approximate Number System (Dehaene, 1997/2011). Early in life, children in numerate societies also learn to describe this system using number words. How do linguistic representations of number become related to nonlinguistic representations of number? We hypothesize that the analogical process of structure mapping (Gentner, 1983) helps children to form mappings between the linguistic and nonlinguistic number systems on the basis of structural similarities between the two systems. To test this, we tested and analyzed 47 four-and-five year olds’ performance on estimation and analogy tasks. We found that analogical reasoning ability uniquely predicted several components of estimation performance, even when controlling for other domain-general cognitive skills. This provides strong evidence that analogical processes are uniquely related to the development of early estimation.