Abstract:Intestinal Segmented Filamentous Bacteria (SFB) is a Gram-positive Clostridium spp. with selective colonization of species, as shown by experiments. SFB mainly colonize on the surface of intestinal epithelial cells at the end of the ileum, to regulate the maturation of host immune system, stimulate the specific differentiation of CD4+ Th17 cells and promote the secretion of intestinal surface immunoglobulin A (sIgA). SFB play very important roles in preventing pathogenic microbial infection and induction of occurrence and development of autoimmune diseases. Although SFB can be detected in many vertebrates, few studies have been reported on human SFB. Studies have shown that SFB can be detected in human intestinal samples, and the investigation of clinical samples shows that there is a certain correlation of SFB in human intestinal tract with immune regulation and disease symptoms. However, due to the extremely low abundance of SFB in human intestinal tract and the possible existence of different SFB strains in the same individual, isolation and pure culture of SFB single bacteria are still the only way to further study the immune regulation function of human SFB.