title: Requirements of a costimulus for IL-4-induced IgE class switching in murine B cells activated via antigen receptors: effectiveness of 8-mercaptoguanosine.
abstract: In the present paper, we investigated the requirements for the induction of IgE responses in murine B cells stimulated via surface Ig receptors by trinitrophenyl (TNP)-LPS or F(ab')2 of anti-mouse IgM (anti-mu) Abs. When murine B cells were cultured with 0.2 microgram/ml TNP-LPS, the secretion of anti-TNP IgM, but not that of IgG1 or IgE, was induced. It should be noted that IL-4, alone or in combination with IL-2 or IL-5, was not sufficient for inducing IgE class switching in these B cells, in contrast to the cells activated polyclonally with 20 micrograms/ml LPS, suggesting that an additional signal is required under the former conditions. After extensive screening of costimuli for inducing IgE in cooperation with IL-4, we found that 8-mercaptoguanosine (8-SGuo), a potent B cell activator, was effective. The addition of 8-SGuo to TNP-LPS-stimulated B cell cultures resulted in the secretion of both anti-TNP IgM and IgG1, but not anti-TNP IgE. Anti-TNP IgE formation was induced only when 8-SGuo was added in combination with IL-4, whereas 8-SGuo plus IL-4 failed to induce IgE secretion in the absence of TNP-LPS. Similar requirements for 8-SGuo and IL-4 for IgE formation were observed when B cells were stimulated with anti-mu. It was revealed that induction of the IgE responses was accompanied by increased frequency of surface IgE+ B cells and the expression of germline and productive epsilon transcripts. In B cells stimulated with anti-mu plus IL-4, 8-SGuo was shown to enhance the expression of the B cell-specific activator protein gene that is thought to be required in IL-4-dependent germline epsilon transcription.
authors.affiliation: Department of Biotechnology, Faculty of Engineering, Okayama University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hikida
authors.forename: T
authors.initials: T
authors.lastname: Takai
authors.forename: H
authors.initials: H
authors.lastname: Ohmori
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D001483:Base Sequence; D004338:Drug Combinations; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006151:Guanosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017578:Immunoglobulin Class Switching / Q000187:drug effects*; D007073:Immunoglobulin E / Q000096:biosynthesis / Q000187:drug effects*; D007075:Immunoglobulin M / Q000276:immunology; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008969:Molecular Sequence Data; D011947:Receptors, Antigen, B-Cell / Q000187:drug effects* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D013872:Thionucleosides / Q000494:pharmacology*; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000888:Antibodies, Anti-Idiotypic; D004338:Drug Combinations; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D013872:Thionucleosides; D014301:Trinitrobenzenes; C044203:anti-IgM; D006151:Guanosine; D015847:Interleukin-4; D007073:Immunoglobulin E; C037031:8-thioguanosine