Complexity of the human memory B-cell compartment is determined by the versatility of clonal diversification in germinal centers.
Our knowledge about the clonal composition and intraclonal diversity of the human memory B-cell compartment and the relationship between memory B-cell subsets is still limited, although these are central issues for our understanding of adaptive immunity. We performed a deep sequencing analysis of rearranged immunoglobulin (Ig) heavy chain genes from biological replicates, covering more than 100,000 memory B lymphocytes from two healthy adults. We reveal a highly similar B-cell receptor repertoire among the four main human IgM(+) and IgG(+) memory B-cell subsets. Strikingly, in both donors, 45% of sequences could be assigned to expanded clones, demonstrating that the human memory B-cell compartment is characterized by many, often very large, B-cell clones. Twenty percent of the clones consisted of class switched and IgM(+)(IgD(+)) members, a feature that correlated significantly with clone size. Hence, we provide strong evidence that the vast majority of Ig mutated B cells--including IgM(+)IgD(+)CD27(+) B cells--are post-germinal center (GC) memory B cells. Clone members showed high intraclonal sequence diversity and high intraclonal versatility in Ig class and IgG subclass composition, with particular patterns of memory B-cell clone generation in GC reactions. In conclusion, GC produce amazingly large, complex, and diverse memory B-cell clones, equipping the human immune system with a versatile and highly diverse compartment of IgM(+)(IgD(+)) and class-switched memory B cells.
Bioinformatics, Faculty of Biology, University of Duisburg-Essen, 45117 Essen, Germany;
Bettina
B
Budeus
Medical Faculty, Institute of Cell Biology (Cancer Research), 45122 Essen, Germany.
Stefanie
S
Schweigle de Reynoso
Medical Faculty, Institute of Cell Biology (Cancer Research), 45122 Essen, Germany.
Martina
M
Przekopowitz
Bioinformatics, Faculty of Biology, University of Duisburg-Essen, 45117 Essen, Germany;
Daniel
D
Hoffmann
Medical Faculty, Institute of Cell Biology (Cancer Research), 45122 Essen, Germany.
Marc
M
Seifert
Medical Faculty, Institute of Cell Biology (Cancer Research), 45122 Essen, Germany ralf.kueppers@uk-essen.de.
Ralf
R
Küppers
D056704:Adaptive Immunity; D000328:Adult; D001402:B-Lymphocytes / Q000166:cytology*; D002469:Cell Separation; D019295:Computational Biology; D004252:DNA Mutational Analysis; D018858:Germinal Center / Q000166:cytology*; D006801:Humans; D017578:Immunoglobulin Class Switching; D007072:Immunoglobulin D / Q000276:immunology; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007075:Immunoglobulin M / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007156:Immunologic Memory; D008297:Male; D009154:Mutation; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000276:immunology
D007072:Immunoglobulin D; D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7
IgM memory; IgV gene repertoire; clonal composition; human memory B cell subsets