CD40 Ligand and Appropriate Cytokines Induce Switching to IgG, IgA, and IgE and Coordinated Germinal Center and Plasmacytoid Phenotypic Differentiation in a Human Monoclonal IgM+IgD+ B Cell Line

• Published in: The Journal of immunology (1950) Vol. 160; no. 5; pp. 2145 - 2157
• Main Authors: Cerutti, Andrea, Zan, Hong, Schaffer, Andras, Bergsagel, Leif, Harindranath, Nagaradona, Max, Edward E, Casali, Paolo
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 01.03.1998
• Subjects: Antibodies, Monoclonal - biosynthesis; B-Lymphocyte Subsets - immunology; B-Lymphocyte Subsets - metabolism; Base Sequence; CD40 Antigens - physiology; CD40 Ligand; CD56 Antigen - genetics; Cell Differentiation - genetics; Cell Differentiation - immunology; Cell Line; Clone Cells; Cytokines - physiology; Gene Rearrangement, B-Lymphocyte - genetics; Germinal Center - cytology; Germinal Center - immunology; Germinal Center - metabolism; Humans; Immunoglobulin A - biosynthesis; Immunoglobulin A - genetics; Immunoglobulin Class Switching - genetics; Immunoglobulin D - biosynthesis; Immunoglobulin E - biosynthesis; Immunoglobulin E - genetics; Immunoglobulin G - biosynthesis; Immunoglobulin G - genetics; Immunoglobulin Heavy Chains - genetics; Immunoglobulin M - biosynthesis; Immunoglobulin M - genetics; Immunoglobulin Variable Region - genetics; Immunophenotyping; Interleukin-4 - physiology; Interleukin-6 - physiology; Ligands; Membrane Glycoproteins - immunology; Membrane Glycoproteins - physiology; Molecular Sequence Data; Plasma Cells - immunology; Plasma Cells - metabolism; Plasma Cells - ultrastructure; Receptors, Antigen, B-Cell - biosynthesis; Sequence Analysis, DNA; Transcription, Genetic - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.160.5.2145

B lymphocytes are induced to undergo Ig class switching and a complex phenotypic differentiation by the milieu of the germinal center. Partly as a result of the lack of a suitable in vitro B cell model, the relationship between these processes in the humans has never been formally established in vitro. We have identified a human monoclonal B cell line, CL-01, that expresses surface IgM and IgD and, upon induction with CD40 ligand, IL-4, and IL-10, switches to all seven downstream isotypes, showing typical DNA switch recombination preceded by germline transcription of targeted CH regions. In CL-01 cells, switch-inducing stimuli trigger concomitant changes in expression of surface IgD, CD23, CD38, and CD77 that parallel those reported in ex vivo isolated tonsillar centroblasts, centrocytes, and memory B cells. Eventually, in the presence of IL-6, CL-01 cells express CD56 and accumulate cytoplasmic IgG and IgA, both traits of plasmacytoid differentiation. Analysis of transcription and recombination of the Ig H locus in sorted CL-01 cells suggest that Ig class switching begins in centroblasts, it extends to all isotypes in centrocytes, and it is extinct in memory B cells. Thus, we have induced coordinated Ig class switching, progression through germinal center phenotypic stages, and differentiation to memory B cells and plasma cells at the level of a single B clonotype. Our data suggest that these processes are likely regulated by a common maturation program, the activation of which may require CD40 ligand, IL-4, IL-10, and IL-6 only.