Ultra-high-scale cytometry-based cellular interaction mapping.

Cellular interactions are of fundamental importance, orchestrating organismal development, tissue homeostasis and immunity. Recently, powerful methods that use single-cell genomic technologies to dissect physically interacting cells have been developed. However, these approaches are characterized by low cellular throughput, long processing times and high costs and are typically restricted to predefined cell types.

Physiological and Pathophysiological Roles of IgM Fc Receptor (FcµR) Isoforms.

IgM is the first antibody to emerge during phylogeny, ontogeny, and immune responses and serves as a first line of defense. Effector proteins interacting with the Fc portion of IgM, such as complement and its receptors, have been extensively studied for their functions. IgM Fc receptor (FcµR), identified in 2009, is the newest member of the FcR family and is intriguingly expressed by lymphocytes only, suggesting the existence of distinct functions as compared to the FcRs for switched Ig isotypes, which are expressed by various immune and non-hematopoietic cells as central mediators of antibody-triggered responses by coupling the adaptive and innate immune responses.

Differences between Human and Mouse IgM Fc Receptor (FcµR).

Both non-immune "natural" and antigen-induced "immune" IgM are important for protection against pathogens and for regulation of immune responses to self-antigens. Since the bona fide IgM Fc receptor (FcµR) was identified in humans by a functional cloning strategy in 2009, the roles of FcµR in these IgM effector functions have begun to be explored. In this short essay, we describe the differences between human and mouse FcµRs in terms of their identification processes, cellular distributions and ligand binding activities with emphasis on our recent findings from the mutational analysis of human FcµR.