Multiple distinct memory B-cell subsets have been identified in humans, but it remains unclear how their phenotypic diversity corresponds to the type of responses from which they originate. Especially, the contribution of germinal centerindependent responses in humans remains controversial. We defined 6 memory B-cell subsets based on their antigen-experienced phenotype and differential expression of CD27 and IgH isotypes.

High-throughput sequencing analysis of hypermutating immunoglobulin (IG) repertoires remains a challenging task. Here we present a robust protocol for the full-length profiling of human and mouse IG repertoires. This protocol uses unique molecular identifiers (UMIs) introduced in the course of cDNA synthesis to control bottlenecks and to eliminate PCR and sequencing errors. Using asymmetric 400+100-nt paired-end Illumina sequencing and UMI-based assembly with the new version of the MIGEC software, the protocol allows up to 750-nt lengths to be sequenced in an almost error-free manner. This sequencing approach should also be applicable to various tasks beyond immune repertoire studies. In IG profiling, the achieved length of high-quality sequence covers the variable region of even the longest chains, along with the fragment of a constant region carrying information on the antibody isotype. The whole protocol, including preparation of cells and libraries, sequencing and data analysis, takes 5 to 6 d.

Mantle cell lymphoma (MCL) is a heterogeneous disease with most patients following an aggressive clinical course while others have an indolent behavior. We performed an integrative and multidisciplinary analysis of 177 MCL to determine whether the immunogenetic features of the clonotypic B cell receptors may identify different subsets of tumors. ‘Truly unmutated’ (100% identity) IGHV genes were found in 24% cases, 40% were ‘minimally/borderline mutated’ (99.9-97%), 19% ‘significantly mutated’ (96.9-95%) and 17% ‘hypermutated’ (<95%). Tumors with high (≥97%) or low (<97%) mutational load used different IGHV genes and their gene expression profiles were also different for several gene pathways. A gene set enrichment analysis showed that MCL with high and low IGHV mutations were enriched in memory and naïve B-cell signatures, respectively. Furthermore, the highly mutated tumors displayed less genomic complexity, were preferentially SOX11 negative, and showed more frequently non-nodal disease. The best cut-off of germline identity of IGHV genes to predict survival was 3%. Patients with high and low mutational load had significant different outcome with 5-year overall survival of 59% and 40%, respectively (P=0.004). Nodal presentation and SOX11 expression also predicted for poor overall survival. In a multivariate analysis, IGHV gene status and SOX11 expression were independent risk factors. In conclusion, these observations suggest the idea that MCL with mutated IGHV, SOX11 negativity, and non-nodal presentation correspond to a subtype of the disease with more indolent behavior.