INTERLEUKIN-21 DIRECTLY AND INDIRECTLY AFFECTS IMMUNOGLOBULIN PRODUCTION BY HUMAN B CELLS

Abstract B cells are not currently known to be capable of producing granzyme B or being cytotoxic. We recently found that human B cells activated with Interleukin 21 (IL-21) and antibodies to the B cell receptor (BCR) or immunostimulatory oligonucleotides (CpG ODN), can produce granzyme B. Further studies were done to assess the biological and potential therapeutic significance of this finding. Granzyme B ELISpot, intracellular staining for granzyme-B, quantitative real time RT-PCR for granzyme B messenger RNA and gene expression array confirmed B cells obtained from the peripheral blood of normal individuals (Fig. 1) and many B cell lines including Namalwa, Daudi, Ramos and EBV-transformed lymphoblasts, can be induced to produce granzyme B. This granzyme B is functional as demonstrated by cleavage of a granzyme B-sensitive colorimetric substrate. IL-21 based treatment also increased the transcription of the gene for perforin and the production of Interferon-γ in select B cell populations. We conclude that IL-21 based therapy can induce B cells to produce functional granzyme B and other components known to be present in the cytotoxic granules of CTL and NK cells. These unexpected findings could have significant implications on our understanding of the role of B cells in immune regulation and for a variety of immune phenomena including auto-, cancer and infectious immunity. Figure 1. Interleukin 21 (IL-21) induces de-novo synthesis of Granzyme B by activated B cells. Peripheral blood mononuclear cells (PBMC) were stimulated with the above depicted agents for 18 hours. After further incubtion with Brefeldin A for 4 hours cells were harvested, fixed, permeabilized, stained with PE- and PE-Cy5-labeled antibodies against Granzyme B and CD19, and analyzed flowcytometrically. Figure 1. Interleukin 21 (IL-21) induces de-novo synthesis of Granzyme B by activated B cells. Peripheral blood mononuclear cells (PBMC) were stimulated with the above depicted agents for 18 hours. After further incubtion with Brefeldin A for 4 hours cells were harvested, fixed, permeabilized, stained with PE- and PE-Cy5-labeled antibodies against Granzyme B and CD19, and analyzed flowcytometrically.

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Signaling of human B cells via toll-like receptors 7 and 8 modulates immunoglobulin production*1

Journal of Allergy and Clinical Immunology ◽

10.1016/j.jaci.2003.12.158 ◽

2004 ◽

Vol 113 (2) ◽

pp. S54

Author(s):

J LYNN

Keyword(s):

B Cells ◽

Toll Like Receptors ◽

Immunoglobulin Production ◽

Human B Cells

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Effect of ozone on immunoglobulin production by human b cells in vitro

Journal of Toxicology and Environmental Health ◽

10.1080/15287399109531573 ◽

1991 ◽

Vol 34 (3) ◽

pp. 353-366 ◽

Cited By ~ 13

Author(s):

Susanne Becker ◽

Jacqueline Quay ◽

Hillel S. Koren

Keyword(s):

B Cells ◽

Immunoglobulin Production ◽

Human B Cells

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CD40 Ligand Determines Whether Interleukin 21 Induces Differentiation of Human B Cells Into Plasma Cells or Into Granzyme B-Secreting Cytotoxic Cells.

Blood ◽

10.1182/blood.v114.22.2675.2675 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2675-2675

Author(s):

Bernd Jahrsdoerfer ◽

Magdalena Hagn ◽

Kai Sontheimer ◽

Elisabeth Schwesinger ◽

Verena Ebel ◽

...

Keyword(s):

B Cells ◽

Confocal Microscopy ◽

Plasma Cells ◽

Conflicts Of Interest ◽

Granzyme B ◽

Cd40 Ligand ◽

Cytotoxic Cells ◽

Spinning Disk ◽

Human B Cells ◽

Interleukin 21

Abstract Abstract 2675 Poster Board II-651 Interleukin 21 (IL-21) is a novel and highly promising cytokine for the treatment of neoplastic and infectious diseases. Recently, IL-21 has been identified as inducer of plasma cell differentiation. Here we show that CD40 ligand is critically involved in this process and that, in its absence, human B cells differentiate into granzyme B (GzmB)-secreting cytotoxic cells rather than plasma cells. GzmB expression and secretion by human B cells was demonstrated by FACS analysis, ELISpot, ELISA, Sensizyme, Western immunoblotting, RT-PCR, and spinning disk confocal microscopy. GzmB secretion requires the presence of IL-21 and B cell receptor engagement, and depends on phosphorylation of JAK1/3 and STAT3. CD40 ligation effectively suppresses GzmB secretion by B cells, suggesting GrB-secreting B cells play a role in the early phase of inflammatory processes, before CD40 ligand-expressing T cells are present. Of note, ex-vivo re-stimulation of B cells from recently vaccinated individuals with inactivated viruses also induces GzmB expression. GzmB is enzymatically active and GzmB-secreting B cells induce apoptosis in various tumor cell lines, a process we were able to visualize by using spinning disk confocal microscopy. Our data reveal an as yet unrecognized role of IL-21-activated B cells, which involves GzmB secretion and cellular cytotoxicity. Our findings may have implications for the understanding of tumor immunosurveillance and early anti-viral immune responses, and may open novel approaches for the immunotherapy of neoplastic and viral diseases. Disclosures: No relevant conflicts of interest to declare.

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