title: Membrane IgM influences membrane IgD mediated antigen internalization in the B cell line Bcl1.
abstract: Signalling through the B cell antigen receptor (BCR) is required for peripheral B lymphocyte maturation, maintenance, activation and silencing. In mature B cells, the antigen receptor normally consists of two isotypes: membrane IgM and IgD (mIgM, mIgD). Although the signals initiated from both isotypes differ in kinetics and intensity, in vivo, the BCR of either isotype seems to be able to compensate for the loss of the other, reflected by the mild phenotypes of mice deficient for mIgM or mIgD. Thus, it is still unclear why mature B cells need expression of mIgD in addition to mIgM. In the present paper, we used the B cell line Bcl1 and investigated the isotype-specific antigen internalization in dependence of co-stimulation of the reciprocal isotype and analysed whether the signal initiated from mIgM is modulated through signalling from mIgD and vice versa. We clearly showed that cross-linkage of mIgM decreases the rate of mIgD mediated antigen internalization and interpret this influence as a unilateral mIgM mediated control on signals initiated at mIgD.
authors.affiliation: University of Salzburg, Department of Molecular Biology, Division Allergy and Immunology Hellbrunnertsrasse 34, A-5020 Salzburg, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Geisberger
authors.forename: Sebastian
authors.initials: S
authors.lastname: Königsberger
authors.forename: Gernot
authors.initials: G
authors.lastname: Achatz
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000918:Antibody Specificity; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007072:Immunoglobulin D / Q000276:immunology*; D007132:Immunoglobulin Isotypes / Q000378:metabolism*; D007075:Immunoglobulin M / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007072:Immunoglobulin D; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell