Our gastrointestinal tract (GIT) is colonized by the intestinal microbiota, a vast community of commensal bacteria which plays an important role in host gut health. Some food products contain live bacteria which transit through our GIT and could exert beneficial effects on our health. Major efforts are focused on these bacteria (known as probiotics) since the last 10 years. Among the numerous proposed health benefits attributed to probiotic and commensal bacteria, their capacity to interact with the host immune system (crosstalk) is now well demonstrated. In this review, we give an overview on the recent developments and perspectives in the study of the role of probiotic and commensal bacteria in human through their crosstalk with the host.