sentence: The type of material obtained , the sequencing depth and the experimental and computational methods used here constitute by far the most thorough and comprehensive analysis of repertoire differences between B cell subsets and isotype subclasses and thereby provide unique insights into the underlying mechanisms , leading to the formation of different B cell subpopulations.Previous work involving human na ï ve and antigen-experienced B cell repertoires havs shown na ï ve B cells to have shorter junctions and higher usage of IGHJ6 and IGHV3 , and lower usage of IGHJ4 and IGHV1 compared with IgM memory and switched B cells ( Briney et al ., 2012a ; Larimore et al ., 2012 ; DeWitt et al ., 2016 ; Bautista et al ., 2020 ) .