Purpose of review: Commensal bacteria in the gut shape the innate and adaptive immune systems of the host. An understanding of how these microbes direct the development of various immune cells will unravel mechanisms underlying host-microbial interaction at the cellular level. In this review, we describe the impact of microbial colonization on the modulation of individual T-cell subsets in health and disease.
Recent findings: Compelling evidence demonstrates that the intestinal microbiota plays a pivotal role in the development of conventional and unconventional T cells both within and outside the intestine. Recent studies have documented an association of specific bacterial species with the development of certain T-cell subsets.
Summary: It is increasingly clear that specific components of the microbiota selectively expand and activate different T-cell subsets under normal and/or pathological conditions. Modulation of the complex microbiota may provide opportunities for the treatment of T-cell-mediated diseases.