Lymphotoxin-alpha is an important autocrine factor for CD40 + interleukin-4-mediated B-cell activation in normal and atopic donors.
Stimulation of human B cells with anti-CD40 + interleukin-4 (IL-4) results not only in proliferation and immunoglobulin E (IgE)-production, but also increased production of the cytokine lymphotoxin-alpha (LT-alpha) (formerly also known as tumour necrosis factor-beta (TNF-beta)). Here, we studied the role of LT-alpha (TNF-beta) in B cells following stimulation with anti-CD40 + IL-4 from normal versus atopic donors. Anti-CD40 + IL-4 stimulation of peripheral blood mononuclear cells (PBMC) from atopic donors resulted in enhanced production of soluble LT-alpha (TNF-beta) and increased membrane LT-alpha (TNF-beta) expression on the B cells compared with normal donors. Functional evaluation of LT-alpha (TNF-beta) in CD40 + IL-4-stimulated B cells shows that recombinant LT-alpha (TNF-beta) induces proliferation of B cells and enhances CD40 + IL-4-mediated B-cell proliferation and IgE synthesis in both normal and atopic donors in a dose-dependent manner. These findings were supported by semiquantitative analysis of epsilon-germline transcripts using reverse transcription-polymerase chain reaction (RT-PCR) showing increased epsilon-germline transcription in the presence of LT-alpha. Furthermore, addition of anti-LT-alpha (anti-TNF-beta) to CD40 + IL-4-stimulated B cells partially inhibited proliferation and IgE synthesis in a dose-dependent manner indicating a role of endogenous LT-alpha (TNF-beta) production by B cells during continued CD40 + IL-4 stimulation. These data suggest that LT-alpha (TNF-beta) plays a potentially significant role during B-cell proliferation and IgE synthesis. Moreover, LT-alpha (TNF-beta) production seems to be differentially regulated in B cells from normal and atopic donors.
Department of Dermatology, Charité-Virchow Klinikum, Humboldt Universität, Berlin, Germany.
M
M
Worm
K
K
Ebermayer
B
B
Henz
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D019013:CD40 Antigens / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000096:biosynthesis; D007139:Immunoglobulin epsilon-Chains / Q000235:genetics; D007150:Immunohistochemistry; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects; D008233:Lymphotoxin-alpha / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000494:pharmacology; D014158:Transcription, Genetic
D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D007139:Immunoglobulin epsilon-Chains; D008233:Lymphotoxin-alpha; D011994:Recombinant Proteins; D015847:Interleukin-4; D007073:Immunoglobulin E